JP2003094219A - Drilling tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drilling tool which assures the rigidity of the drill body and improved ability to discharge cutting chips. SOLUTION: The drilling tool comprises a tool body 1 rotated around the axis O. The tool body 1 is provided with chip discharging flutes 11 on the outer peripheral of cutting edges 2 at the top of the body 1. Cutting edges 8A are provided on walls 11A of the chip discharging flutes 11 oriented in the tool rotating direction T. The chip discharging flutes 11 are formed so that the flute width B increases gradually as goes to the rear end side, at least in a range N on the rear end side of the cutting edges 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a chip discharge groove formed on the outer periphery of a cutting edge portion on the tip side of a tool body rotated around an axis, and the tip of a wall surface of the chip discharge groove facing the tool rotation direction. The present invention relates to a drilling tool provided with a cutting blade and used for drilling a workpiece mainly made of a metal material.

[0002]

2. Description of the Related Art As such a drilling tool, for example, those shown in FIGS. 3 to 6 have been proposed. In the drilling tools shown in these figures, the tip side (left side in FIG. 3) of the substantially cylindrical tool body 1 rotated around the axis O in the tool rotation direction T around the axis O is the cutting edge portion 2. On the outer periphery of the cutting edge portion 2, a pair of chip discharge grooves 3, 3
From the tip end surface of the cutting edge portion 2, that is, the tip end surface 4 of the tool body 1 toward the rear end side (right side in FIG. 3) so as to be symmetrical with respect to the axis O, and further toward the rear end side. It is formed in a spiral shape that twists backward around the axis O in the tool rotation direction T. Here, the rear end portion of the tool body 1 is a shank portion 5 having a diameter one step larger than that of the cutting edge portion 2 on the front end side, and between the shank portion 5 and the cutting edge portion 2. A taper portion 6 having a diameter gradually increasing toward the rear end side is formed, and the chip discharge grooves 3 and 3 are rounded up in the taper portion 6 to the outer peripheral side.

On the other hand, the tool rotation direction T of the chip discharge grooves 3 and 3
At the tip of the wall surface 3A facing the side, chip mounting seats 7, 7 are formed so as to open to the tip surface 4, respectively,
A throw-away tip 8 made of a hard material such as a cemented carbide has a cutting edge 8A projecting toward the tip side beyond the tip surface 4 on these tip mounting seats 7, 7, and a clamp screw 9
It is detachably attached by. In the drilling tools shown in these figures, the tip mounting seats 7, 7 and the throw-away tips 8, 8 and the cutting blades 8A, 8A provided at the tips of the chip discharge grooves 3, 3 and the cutting edges 8A, 8A are also mutually related with respect to the axis O. They are formed and arranged so as to be symmetrical. Further, the tool body 1 is provided with a cutting oil supply hole 1A from the rear end thereof along the axis O, and the supply hole 1A is branched into two parts on the tip side of the cutting edge part 2 and the above-mentioned tip ends are respectively formed. The surface 4 is opened. In such a drilling tool, the tool body 1 is rotated around the axis O in the tool rotation direction T, and is fed to the tip end side in the axis O direction to cut the workpiece with the cutting edges 8A, 8A. Then, a machining hole is bored, and the chips generated by the cutting blades 8A, 8A at that time are sent to the tool rear end side through the chip discharge grooves 3 and 3 and discharged from the machining hole.

[0004]

By the way, in such a drilling tool, the chip discharge grooves 3 and 3 for discharging chips as described above generally have a cutting edge portion as shown in FIGS. 4 to 6. The groove width B is constant over the entire length of 2, and therefore the groove width ratio of the groove width B to the width A of the land 10 defined between the chip discharge grooves 3 and 3. B / A
Is constant over the entire length of the cutting edge portion 2. In addition,
FIG. 6 shows a state in which the chip discharge groove 3 formed in a spiral shape is extended such that the center line in the width direction of the groove width B having such a constant width is parallel to the axis O, It is the simplified side view seen from the direction where the center line coincides with the axis O. However, the cutting edge 8A is shown by a rotation locus around the axis O thereof.

Therefore, in such a drilling tool, the groove width B and the groove width ratio B / are intended to increase the cross-sectional area of the chip discharge groove 3 in order to improve the chip discharge property.
If A is increased, the cross-sectional area of the tool body 1 will decrease over the entire length of the cutting edge portion 2, which will impair the rigidity of the tool body 1 and cause chatter vibration during drilling. In some cases, the tool body 1 may be broken at the cutting edge portion 2. Further, as a device for improving the chip discharging property while preventing such a decrease in the rigidity of the tool body, for example, in Japanese Patent Laid-Open No. 62-2113911, a chip discharging groove is spirally formed on the tip side of a cutting blade portion. And on the rear end side of this, a straight line parallel to the axis O,
It is also proposed to make the groove width ratio of this straight chip discharge groove larger than the groove width ratio of the twisted chip discharge groove, but in this drilling tool, the tip side of the tip side which is constant with a small groove width is proposed. Since the groove width suddenly increases at the part where the width of the twist groove fluctuates to the linear chip discharge groove on the rear end side which is made constant with a large width, the tool body at the tip side of this linear chip discharge groove increases. Since the cross-sectional area is greatly reduced, in other words, the thickness of the tool body is cut off more than necessary at this portion, the deterioration of the tool rigidity cannot be avoided.

The present invention has been made under such a background, and in the drilling tool as described above, it is possible to more reliably secure the rigidity of the tool body and to improve the chip discharging property. The purpose is to provide a possible drilling tool.

[0007]

In order to solve the above problems and to achieve such an object, the present invention provides a chip discharge groove on the outer periphery of the cutting edge portion on the tip side of a tool body rotated around an axis. With a drilling tool formed with a cutting blade provided at the tip of the wall surface of the chip discharge groove facing the tool rotation direction of the chip discharge groove, the chip discharge groove, at least in the range of the rear end side of the cutting edge portion, The groove width is formed so as to gradually increase toward the rear end side. Therefore, according to such a drilling tool, since the groove width of the chip discharge groove is configured to gradually increase at least at the rear end side of the cutting edge portion, it is possible to reduce the thickness of the tool body more than necessary. None, that is, without unnecessarily degrading the tool rigidity, it is possible to secure a large cross-sectional area of the chip discharge groove and improve the chip discharge performance.

Here, the chip discharge groove may be formed so that the groove width gradually increases toward the rear end side over the entire length of the cutting edge portion. In the portion just behind the cutting edge on the tip side, the chips flow out as they are pushed out to the rear end side of the tool body by the pushing force due to the growth at the time of their generation, so it is possible to secure a certain degree of dischargeability. . For this reason, the chip discharge groove has a constant groove width in the range on the front end side of this cutting edge portion, and is formed so that the groove width gradually increases toward the rear end side in the range on the rear end side of this. Maybe,
In this case, it is possible to further secure the rigidity of the tool body.

[0009]

1 and 2 show a first and a second embodiment of the present invention, respectively, and like the one shown in FIG. 6, their chip discharge grooves 11, respectively.
12 is a simplified side view of the groove width B of FIG. 12 viewed from a direction in which the center line coincides with the axis O, assuming a state in which the center line in the width direction extends parallel to the axis O. FIG. In addition,
In the first and second embodiments, the chip discharge grooves 11 and 21 are different from the chip discharge groove 3 of the drilling tool shown in FIGS. The parts are assigned the same reference numerals as those of the drilling tool shown in FIGS. 3 to 6 to simplify the description.

That is, also in these first and second embodiments, the outer circumference of the cutting edge portion 2 on the tip side of the tool body 1 rotated in the tool rotation direction T around the axis O is paired in the first embodiment. The chip discharge grooves 11, 11 of the second embodiment, and in the second embodiment, the pair of chip discharge grooves 12, 12 open symmetrically with respect to the axis O toward the front end surface 4 of the cutting blade portion 2 and head toward the rear end side. Accordingly, it is formed in a spiral shape twisted rearward in the tool rotation direction T around the axis O, and is rounded up to the outer peripheral side in the taper portion 6 on the rear end side of the cutting blade portion 2. In addition, the wall surfaces 11A and 12 of the chip discharge grooves 11 and 12 that face the tool rotation direction T.
A cutting edge 8A is provided at the tip of A by, for example, attaching a throw-away tip 8 (not shown).

Then, in the first embodiment shown in FIG.
On the tip end side of the cutting edge portion 2, the chip discharge groove 11 is provided with the front end face 4
The groove width B of the chip discharge groove 11 is made constant within a range M from the tip position opened to the predetermined length L in the direction of the axis O, and in the range N on the rear end side of the cutting blade portion 2 than this. The groove width B is gradually increased. Here, in the first embodiment, the groove width B is designed to increase at a constant rate of increase in the range N in which the groove width B gradually increases, and therefore the width A of the land 10 is reversed. The groove width ratio B / A is increased at a constant rate. Further, in the range N on the rear end side, the chip discharge groove 11 is configured such that the center line in the width direction thereof continuously reaches the taper portion 6 at a twist angle equal to the center line in the range N on the front end side. For example, the wall surface 11 facing the tool rotation direction T when the chip discharge groove 11 having a constant width in the range N on the tip end side is extended to the rear end side with the same width.
The groove width B is increased such that A and the wall surface 11B facing the rear side of the tool rotation direction T are equal in size to each other and are spread in the circumferential direction toward the rear end side at a constant rate.

Therefore, in the drilling tool of the first embodiment having such a configuration, the above range N on the rear end side of the cutting edge portion 2 is obtained.
In, the groove width B of the chip discharge groove 11 is gradually increased toward the rear end side.
Since a large cross-sectional area can be ensured in the range N on the rear end side, the chip discharging property can be improved. On the other hand, in the range M on the tip side near the cutting edge 8A where the chips are sent to the rear end side by the pushing force due to the growth, the groove width B of the chip discharge groove 11 is constant, and this tip range From the rear end position of M to the rear end side range N, the groove width B is gradually increased at a constant increase rate from the width made constant in the front end side range M, that is, the groove width B is constant. Since the tool body 1 is gradually increased in proportion, the wall thickness of the tool body 1 at the tip side of the tip end side range M and particularly the tip end side of the rear end side range N is not excessively shaved more than necessary. The tool rigidity is not impaired due to the improvement in workability.

In the first embodiment, the range M on the tip end side where the groove width B of the chip discharge groove 11 is constant is too long in the direction of the axis O, and the pushing force due to the growth of chips causes the tip end to have the above-mentioned pushing force. Since it does not work on the rear end side of the side range M, and the rear end side range N in which the groove width B gradually increases is shortened, it may become impossible to improve the chip discharging property. . Therefore, even when the range M in which the groove width B is made constant is provided on the tip side of the cutting edge portion 2 as in the first embodiment, the predetermined length L in the direction of the axis O is as shown in FIG. As shown in, the diameter of the circle formed by the outer peripheral edge of the cutting blade 8A around the axis O as the length from the outer peripheral edge of the cutting blade 8A, that is, 1 × D to 2 × with respect to the outer diameter D of the cutting blade 8A.
It is desirable to set it in the range of D. On the other hand, the lower limit value of the length L may be 0, that is, as in the second embodiment shown in FIG. The cutting edge portion 2 may be configured to gradually increase toward the side, that is, the total length of the cutting edge portion 2 may be the same as the range N in the first embodiment as illustrated. In this case, the chip discharge groove 12 toward the rear end side
The increase rate of the groove width B of the cutting edge portion 2 may be constant over the entire length of the cutting edge portion 2, and for example, the length L set in the above range.
Of the cutting edge portion 2 and the range on the rear end side of the cutting edge portion 2 are different from each other, for example, by increasing the increase rate to be constant and the rear end side range to be larger than the front end side range. You may make it a rate. Also, these first and second
In the embodiment, the increasing rate of the groove width B of the chip discharge grooves 11 and 12 that gradually increases toward the rear end side may be changed stepwise or continuously.

Further, in the first embodiment, in the range N in which the groove width B on the rear end side of the cutting edge portion 2 gradually increases as described above, the front end side range M in which the groove width B is constant is set. When the chip discharge groove 11 is extended to the rear end side with the same twist angle and groove width, a wall surface 11A facing the tool rotation direction T side of the chip discharge groove 11 and a wall surface 11B facing the rear side thereof are provided.
The widthwise center lines of the chip discharge grooves 11 in the rear end side range M are constant in the groove width B in the front end side range M so that they are expanded in the circumferential direction at the same size and at the same rate of increase toward the rear end side. The chip discharge groove 11 is formed to have the same twist angle continuously with the widthwise center line of the chip discharge groove 11.
Is formed in a spiral shape over the entire length of the cutting edge portion 2, and the effect of pushing out the chips by the rotation of the tool body 1 during drilling works even up to the rear end of the cutting edge portion 2, so that it is more reliable. Chips can be discharged. In this respect, for example, the above-mentioned Japanese Patent Laid-Open No. 62-62
Like the drilling tool disclosed in Japanese Patent Publication No. 213911, the chip discharge groove is formed by being bent with respect to the spiral tip end side so as to extend parallel to the axis of the tool body on the rear end side of the cutting edge portion. If this is done, chip clogging is likely to occur at this bent portion, and since the above-mentioned pushing effect does not work on the rear end side, although the total length of the chip discharge groove itself becomes short, smooth chip discharge may be impaired. .

However, even if the chip discharge groove 11 is formed in a spiral shape over the entire length of the cutting edge portion 2 as in the first embodiment, the tip end side range M having a constant groove width B as in the present embodiment. Both of the wall surfaces 11A and 11B facing the tool rotation direction T and the tool rotation direction T rearward in the rear end side range N of the chip discharge groove 11 of FIG.
In the circumferential direction, the groove width B is gradually increased, and one of the wall surfaces 11A and 11B is formed so as to be twisted at a constant twist angle in the front and rear end side ranges M and N, and the other is formed to the rear. The groove width B may be gradually increased by gradually expanding in the circumferential direction in the end side range N toward the rear end side. However, such a spiral chip discharge groove of a drilling tool generally fixes and rotates a cutting tool such as a ball end mill in a fixed position, and at the same time, aligns the tool body 1 with the twist of the chip discharge groove. It is formed so as to cut the outer periphery of the cutting edge portion 2 by advancing it while rotating it about the axis O, but in the case of adopting the above configuration, first, the chip discharge groove 11 in the tip end side range M is formed.
A chip discharge groove is formed in the entire length of the cutting edge portion 2 in accordance with the twist of the wall surface 11A of the rear end side range N or the wall surface 1
It suffices to cut 1B with a twist according to its spread. When expanding both wall surfaces 11A and 11B as in the first embodiment, cutting in the tip end side range M also needs to be cut three times. However, it only needs to be cut twice. In particular, if the wall surface 11A facing the tool rotation direction T side is smoothly continuous with a constant twist angle in the front and rear end side ranges M and N, the pushing effect does not fluctuate over the entire length of the cutting edge portion 2 and is more stable. The discharged chips can be promoted.

Further, in the above-described drilling tool in which the groove width B is gradually increased at least in the rear end side range N of the cutting edge part 2, the cutting edge part 2 is in the rear end side range N. Since the cross-sectional area becomes small, it is unavoidable that the rigidity of the tool body 1 is reduced. Therefore, in order to secure the rigidity, the diameter of the circle that is in contact with the bottom surface of the chip discharge grooves 11 and 12 about the axis O in the cross section orthogonal to the axis O, that is, the core thickness of the tool body 1 at the cutting edge portion 2 is It is desirable that the groove width B is gradually increased toward the rear end side in at least the rear end side range N of the cutting edge portion 2 where the groove width B is gradually increased.
When the core thickness is increased in this manner, the cross-sectional area of the chip discharge grooves 11 and 12 is reduced by that amount, and there is a risk that the above effect due to the groove width B being gradually increased is impaired. Therefore, in order to more reliably improve the chip discharging property, the core thickness is made constant even in the range N in which the groove width B gradually increases toward the rear end side, or conversely to the above. It is desirable to make it gradually smaller. In addition, in the first and second embodiments, the throw-away tip 8 is detachably attached to the tip of the cutting edge portion 2 and the cutting edge 8A is provided, as in the drilling tool shown in FIGS. 3 to 6. The present invention is applied to a throw-away type drill provided at the tips of the chip discharge grooves 11 and 12. For example, a cutting edge chip having a cutting edge other than such a throw-away type drill is used. It is of course possible to apply the present invention to a brazing drill that is brazed to the tip of the cutting portion or to a solid drill in which the cutting edge is directly formed on the tool body at the tip of the cutting edge portion.

[0017]

As described above, according to the present invention,
The rigidity of the cutting edge is secured by gradually increasing the groove width of the chip discharge groove formed on the outer periphery of the cutting edge on the tip side of the tool body at least at the rear end side of the cutting edge toward the rear end side. However, it is possible to improve the chip discharge performance, which makes it possible to perform smooth and stable drilling while preventing chatter vibration of the tool body during drilling and accidental breakage. Becomes

[Brief description of drawings]

FIG. 1 shows the first embodiment of the present invention, assuming that the chip discharge groove 11 has a groove width B extending along a center line in the width direction so as to be parallel to an axis O. FIG. 6 is a simplified side view seen from a direction coinciding with an axis O.

FIG. 2 shows a second embodiment of the present invention, assuming that the center line of the chip width of the chip discharge groove 12 is extended so as to be parallel to the axis O. FIG. 6 is a simplified side view seen from a direction coinciding with an axis O.

FIG. 3 is a side view showing an example of a conventional drilling tool.

4 is a sectional view taken along line YY in FIG.

5 is a ZZ sectional view in FIG.

6 is a perspective view of the drilling tool shown in FIG. 3, where the center line of the chip width of the chip discharge groove 3 is extended so as to be parallel to the axis O; It is the simplified side view seen from the direction which corresponds.

[Explanation of symbols]

1 Tool Main Body 2 Cutting Edge 8A Cutting Edges 11 and 12 Chip Discharge Grooves 11A and 12A Wall Surfaces of the Chip Discharge Grooves 11 and 12 that Face the Tool Rotation Direction T Axis T of the Tool Body 1 Tool Rotation Direction M Tip of the Cutting Edge 2 Side range N Range of the cutting edge 2 on the rear end side B Groove width

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhiko Kawade             1528, Nakashinden, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture             Address Mitsubishi Materials Corporation Gifu Factory             Within F term (reference) 3C037 DD01

Claims (3)

[Claims] 1. A chip discharging groove is formed on the outer periphery of a cutting edge portion on the tip side of a tool body rotated around an axis, and a cutting blade is provided at the tip of a wall surface of the chip discharging groove facing the tool rotation direction. In the drilling tool, the chip discharge groove is formed so that the groove width gradually increases toward the rear end side in at least the range of the rear end side of the cutting edge portion. Dawn tool. 2. The chip discharge groove has a constant groove width in the range on the front end side of the cutting edge portion, and in the range on the rear end side thereof, the groove width gradually increases toward the rear end side. The drilling tool according to claim 1, wherein the drilling tool is formed to have 3. The chip discharge groove is formed so that the groove width gradually increases toward the rear end side over the entire length of the cutting edge portion. The described drilling tool.