JPH11104911A - Drilling tool, and throw-away type drilling tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a cutting precision by restraining deflection of a tool main body due to a cutting load at the time of biting. SOLUTION: Each cutting edge 23 of a tip 18 is formed of the first cutting edge 25 and the second cutting edge 26 via a step difference, and the first cutting edge 25 is protruded to more outward than the second cutting edge 26. An external edge tip 18a and an internal edge tip 18b comprising the tip 18 are attached in the tip of a tool main body 11 to protrude the tip 18b to the tip side more than the tip 18a. The first cutting edge 25 near the axis of rotation O is protruded to the tip side more than the second cutting edge 26 in the each cutting edge 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drilling tool such as a drill used for drilling and the like and a throw-away type drilling tool.

[0002]

2. Description of the Related Art Conventionally, an example of a throw-away type drill is disclosed in Japanese Patent Application Laid-Open No. 9-150304. This drill will be described with reference to FIGS. 11 and 12. The drill 1 includes a shank portion 2 and a blade portion 3.
A pair of chip discharge grooves (flutes) that are linear or spiral along the rotation axis O of the drill body 1 a are provided on the outer peripheral surface of the blade 3.
4 is formed from the base end to the distal end surface. At the tip of each chip discharge groove 4 intersecting with the tip face 3a of the blade 3, two substantially parallelogram plate-like throw-away tips 6, 6 are attached. This indexable insert 6 has a cutting edge 8 composed of a main cutting edge 7 bent in a substantially U-shape at the ridge of the upper surface and two cutting edges 8b and 8c formed in a substantially mountain shape via a step 8a. Are formed for each pair of rotation targets. And, of the throw-away tips 6, the throw-away tips 6 forming the inner blade tips 6a are formed.
The main cutting edge 7 protrudes toward the distal end at a position close to the rotation axis O of the drill 1, and the indexable tip 6, which forms the outer cutting tip 6 b, has a distal end where the cutting edge 8 is far from the rotation axis O. It is provided to protrude to the side.

[0003] In cutting, the work material is cut by a main cutting edge 7 serving as an inner blade and a cutting blade portion 8 serving as an outer blade, and holes are formed. In particular, the cutting blade portion forming an outer blade is used. In 8, the outer cutting edge 8b projects on the work material first during cutting because the outer cutting edge 8b protrudes more distally than the inner cutting edge 8c. Since the cutting edge portion 8 of the outer blade tip 6b is separated into the two cutting edges 8b and 8c via the step 8a, chips are generated in a state where the chips are separated by the step 8a during cutting, and each chip is generated. The discharge property is improved due to the thinness.

[0004]

By the way, the cutting edge 8b outside the cutting edge portion 8 is located farthest in the radial direction from the rotation axis O of the drill 1, so that the moment is large and the cutting resistance at the time of biting is large. . Moreover, since the distance from the gripping portion of the shank portion 2 of the drill 1 to the cutting edge portion 8 is large, the drill 1 is bent and elastically deformed by the cutting load at the start of cutting, so that the drill 1 is elastically deformed outside the tool body 1a in the radial direction. The tip of the drill 1 is bent and pulled toward the wall surface side of a certain processing hole, and the entrance of the processing hole is cut wide to partially expand the diameter, resulting in a decrease in hole processing accuracy.
Further, compared with the chips formed by the cutting edge portion 8, the chips formed by the main cutting edge 7 have a disadvantage that the chips are wide and the dischargeability through the chip discharging groove 4 is relatively poor because the chips are not divided.
In view of such problems, an object of the present invention is to provide a drilling tool capable of performing stable cutting at the time of biting and performing drilling with high precision.

[0005]

According to the present invention, there is provided a drilling tool in which a cutting edge provided with a first cutting edge and a second cutting edge is protruded from a tip end side of a tool body through a step. The tool is characterized in that the first blade at a position close to the rotation axis of the tool main body is provided so as to protrude more distally than the second cutting blade at a position far from the rotation axis. Further, the throw-away type drilling tool according to the present invention is directed to a throw-away type drilling tool in which a cutting edge provided with a first cutting edge and a second cutting edge is protruded toward the front end side of the tool main body through a step on the front end surface of the tool main body. In a throw-away type drilling tool to which a tip is attached, a first cutting edge located close to the rotation axis of the tool body is provided so as to protrude more distally than a second cutting edge located far from the rotation axis. It is characterized by the following. Since the first cutting edge that projects further to the tip side is located close to the axis of rotation of the tool body, the moment applied to the first cutting edge at the start of cutting is relatively small, so the cutting end of the tool body is With this, it is possible to suppress outward bending, and high-precision cutting can be performed.

The indexable insert is composed of an outer cutter tip located on the outer peripheral side with respect to the rotation axis of the tool body and an inner cutter tip located on the inner side, and the cutting edge of the inner cutter tip is the cutting edge of the outer cutter tip. It may project to the tip side from the blade.
Since the moment applied to the first blade by the cutting resistance at the time of the first biting becomes small, the bending of the tool main body to the outside is further suppressed, so that more accurate cutting can be performed. Further, the first cutting edge of the outer cutting tip may protrude from the second cutting edge of the inner cutting tip to the distal end side, and may be retracted to the base end side from the first cutting edge of the inner cutting tip. Further, the inner cutter tip and the outer cutter tip may be a throw-away tip having the same shape and the same size. By using a plurality of the same chips, the running cost is low, and the management and mounting of the chips are easy.

[0007]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIGS. 1 is an overall view of a throw-away type drill according to an embodiment, FIG. 2 is an enlarged view of a cutting edge portion in FIG. 1, FIG. 3 is a front end view of the drill shown in FIG. 1, and FIG. 5 is a plan view of the throw-away tip, and FIG. 6 is a sectional view of the tip shown in FIG.
7 is a diagram showing a cutting state of the drill with the cutting edge, wherein FIG. 7 (a) is a diagram showing a chip generation state of the inner blade tip, and FIG. 7 (b) is a diagram showing a chip generation state of the outer blade tip. FIG. 1 to 4, a throw-away drill 10 is shown.
The drill body 11 includes a shank portion 12 and a blade portion 13. The drill tip shown in FIG. 3 is provided with a pair of substantially fan-shaped land portions 14 with the core thick portion 9 interposed therebetween.
4, a pair of chip discharge grooves 15 are formed to face each other,
The chip discharge groove 15 is formed by cutting the outer peripheral surface along the rotation axis O of the drill body 11 into a spiral shape (or a straight line shape). The land 14 may be either a positive brand or a negative brand. Each chip discharge groove 15 is substantially fan-shaped at the tip end of the drill body 11 when viewed from the tip end,
The base end near the shank portion 12 has an arc-shaped cross section as shown in FIG. 4, and is formed so that its cross section gradually changes from the tip end side to the base end side.

[0008] Tip mounting seats 16a and 16b are formed at the tips of the wall surfaces of the chip discharge grooves 15 facing the rotation direction, and throw-away tips 18 and 18 of the same shape and size are mounted on the respective chips by clamp members such as screws. Have been. The throw-away tip 18 is, as shown in FIGS. 5 and 6,
The surface is substantially an equilateral triangular plate, and the surface facing the lower surface 19 forming the seating surface is an upper surface 20, and the side surface 21 is a positive chip that is inclined outward from the lower surface 19 toward the upper surface 20.
At the center of the upper surface 20, a hole 22 for screw insertion that penetrates to the lower surface 19 is formed. On the upper surface 20, the ridges forming substantially three sides are each a cutting edge 23, and each cutting edge 23 is separated into, for example, a first cutting edge 25 and a second cutting edge 26 via a step 24 near the center. . In plan view of the upper surface 20,
The first blade 25 is formed to protrude outward from the second cutting blade 26.

Here, on the upper surface 20 shown in FIG. 5, a point C is set at the center of each corner ridge, and an angle formed by a line CC connecting the adjacent points C and α (≧
60 °), the line segment CC and the first blade 25 facing the line segment CC.
Is β (2 ° ≦ β ≦ 10 °), and the angle between the line segment CC and the second cutting edge 26 facing the line segment is γ (2 ° ≦ γ).
≤ 10 °). Then, 60 ° ≦ α + β + γ ≦ 80
゜. Also, the boundary between the first blade 25 and the step 24 is D
If the boundary between the second cutting edge 26 and the step 24 is point E, the distance between CDs is m, and the distance between CEs is n, even if one of the distances m and n is larger than the other. Good or the same. On the upper surface 20, a land 28 is provided all around the inside of each cutting edge 23, and a breaker groove 29 is formed inside the land 28.

In the throw-away type drill 10 shown in FIG. 2, the tip mounting seat 16a is formed on the outer peripheral side of the drill body 11 away from the rotation axis O, and the throw-away tip 18 mounted on the tip mounting seat 16a is connected to the outer blade tip 18a. I do. When the outer blade tip 18a is in the mounted state, the cutting blade 23 protrudes toward the distal end side with respect to the drill body 11, and furthermore, the first blade 25a.
Are arranged inside and the second cutting blade 26 is arranged outside and fixed. Therefore, the first blade 25 is the second cutting blade 26.
And the inner end thereof is at a position separated from the rotation axis O. In addition, the tip mounting seat 16
“b” is formed inside the drill body 11 near the rotation axis O, and the indexable insert 18 mounted on the drill body 11 is referred to as an inner blade tip 18b. When the inner blade tip 18b is mounted, the cutting blade 23 projects toward the distal end side with respect to the drill body 11, and the first cutting blade 25 is disposed inside and the second cutting blade 26 is disposed outside and fixed. I have. 25th blade
Protrudes more distally than the second cutting edge 26, and its inner end crosses the rotation axis O and protrudes in a region opposite to the rotation axis O.

Then, the outer blade tip 18a and the inner blade tip 1
When the cutting blades 23 of the inner blade tip 18b of the inner blade tip 18b protrude to the most distal end side when the respective cutting blades 23 of the inner blade tip 18b are viewed over the rotation locus of the drill body 11 about the rotation axis O as shown in FIG.
The first blade 25 of the outer blade tip 18a is located between the first blade 25 and the second cutting blade 26 of the inner blade tip 18b, and the outer blade 25 is located on the base end side of the second blade 26 of the inner blade tip 18b. The second cutting blade 26 of the blade tip 18a is located. In addition, appropriate lead angles θ1 and θ2 are given to the first blades 25 of the outer blade tip 18a and the inner blade tip 18b, respectively. Further, as shown in FIG. 7, each cutting edge 23 of the outer blade tip 18a and the inner blade tip 18b is assumed to be continuous on its rotation locus. Therefore, at the start of cutting, the inner blade tip 18b is first cut at the rotation axis O side end of the first blade 25, and the outer blade tip 18a is cut at the rotation axis O side end of the first blade 25. You will eat the wood. Further, an oil hole 30 is formed in the center of the drill body 11, and the tip is forked at the tip and discharged from the openings 30a and 30b shown in FIG.

Since the indexable drill 10 according to the present embodiment is constructed as described above, when drilling with this drill 10, first, the inner cutter tip 18b
The cutting edge 25 of the first abuts against the work material and starts cutting.
At that time, the inner end of the first blade 25 provided with the lead angle first comes into contact with the workpiece. Then, subsequently, the first blade 25 of the outer blade tip 18a starts cutting at its inner end. Therefore, at the start of cutting, as shown in FIG. 7, the cutting is started by each of the first blades 25 near the rotation axis O of the inner cutter tip 18b and the outer cutter tip 18a, so that cutting at the time of biting is performed. Even if a load is applied to the drill body 11 due to resistance, the distance from the rotation axis O to each of the first blades 25 is relatively short and the moment is small, so the amount of elastic deformation of the drill body 11 due to the load is small, and the drill body 11 Cutting the inner wall of the machined hole by bending radially outward is effectively suppressed. Since the cutting edges 23 of the inner cutting edge 18b and the outer cutting edge 18a are separated into the first cutting edge 25 and the second cutting edge 26 via the step 24, the chips are separated into two pieces. And is smoothly discharged through the chip discharge groove 15.

As described above, according to the present embodiment, at the time of biting, the cutting of the inner blade tip 18a and the outer blade tip 18b is started by the first blade 25 near the rotation axis O. The deflection of the cutting edge portion 13 in the radially outward direction due to the bending of the drill body 11 due to the load at the time of biting is small, and the inner wall near the entrance of the machining hole is reliably suppressed from being cut and expanded, thereby achieving high precision. Drilling can be achieved. Moreover, at the time of cutting, each cutting edge 23 of the inner blade tip 18b and the outer blade tip 18a is
And the second cutting blade 26, the chips are generated in a finely divided state, and the discharge of chips through the chip discharge groove 15 is improved.

Hereinafter, modified examples of the throw-away tip 18 used in the above-described embodiment will be described with reference to FIGS. 8 to 10, but the same or similar parts as those of the throw-away tip 18 shown in the above-described embodiment will be described. The description is omitted using the same reference numerals. FIG. 8 is a plan view showing a first modification of the throw-away tip 18 shown in the above embodiment. 8, the throw-away tip 32 is a substantially square plate-like positive tip, and each side portion forming the ridge line of the upper surface 20 has a cutting edge 23 including a first cutting edge 25 and a second cutting edge 26 via a step 24, respectively. It has been. Upper surface 20
The angle α formed between the line segment CC connecting the adjacent corner center points C, C and the line segment CC is ≧ 90 °, and the angle β formed between the line segment CC and the first blade 25 opposite thereto is , 2 ゜ ≦ β
≦ 10 °, and the angle γ between the line segment CC and the second cutting edge 26 opposed thereto is 2 ° ≦ γ ≦ 10 °. Then, 90 ° ≦ α + β + γ ≦ 110 °.

FIG. 9 is a plan view showing a second modification of the throw-away tip 18 shown in the above embodiment. In this modified example, the throw-away tip 34 has a substantially equilateral triangular plate shape substantially similar to the throw-away tip 18 in the embodiment, and the first cutting edge 25 and the second cutting edge 26 ′ are interposed via the step 24. In each of the cutting edges 33, the second cutting edge 26 'is located on the line segment CC, and γ =
0 °, the above-mentioned throw-away tip 1
8 is different. Next, FIG. 10 is a plan view showing a third modification of the throw-away tip 18 shown in the above embodiment. In this modification, the throw-away tip 36
Has substantially the same shape as the throw-away tip 32 in the second modified example. In each cutting edge 33, the second cutting edge 26 ″ is located on the line segment CC, and γ = 0 °. This is different from the above-mentioned throw-away tip 32. The throw-away tip 32 according to these modified examples,
The cutting edges 23, 33 are set at the same position and angle as the throw-away tip 18 in the above-described embodiment.
May be mounted on the drill 10 so as to be positioned.

In the above description, regarding the throw-away tips 18 (32, 34, 36), the outer cutter tips 18
a, the outer blade tip 18a is positioned so as to protrude toward the distal end side from the inner blade tip 18b. The first blade 25 of the inner blade tip 18b may be located between the first blade 25a and the second cutting blade 26 of the blade 18a. Further, in the embodiment, the first blades 25 are provided via the steps 24, 24 so that the chips generated by the cutting blades 23, 33 of the outer blade tip 18a and the inner blade tip 18b are each divided into two. And the second cutting blades 26, 26 ', 26 "are provided, but each cutting blade 23 may be provided with two or more steps, and may be constituted by three or more cutting blades. Is generated in a state of being separated into three or more parts.In this case as well, it is preferable that the cutting edge closest to the rotation axis O protrudes most distally (the second cutting edge). May protrude most distally).

In the above description, the throw-away tips 18, 32, 34, and 36 have the same shape for each of the cutting edges 23, 33 at the respective ridges. The blade 23 and the cutting blade 33 may be formed. In the above example, the chips 18, 3
Although the cutting blades are provided only on the upper surface 20 of 2, 34, 36, the cutting blades may be provided on both upper and lower surfaces.

[0018]

As described above, according to the drilling tool and the indexable drilling tool according to the present invention, the second cutting edge at a position close to the rotation axis of the tool main body is located at a position far from the rotation axis. Since it is provided so as to protrude to the tip side from the cutting edge, the moment applied to the first cutting edge at the start of cutting is relatively small, so that the tip end of the tool body can be suppressed from bending radially outward due to the cutting load. Thus, high-precision hole machining and cutting can be performed without increasing the diameter of the opening of the machining hole.

The indexable insert comprises an outer cutter tip located on the outer peripheral side with respect to the rotation axis of the tool body and an inner cutter tip located on the inner side, and the cutting edge of the inner cutter tip is the cutting edge of the outer cutter tip. Since it protrudes from the cutting edge to the tip side, the moment acting on the first cutting edge due to the cutting resistance at the start of cutting is further reduced, so that the tool body is less bent outward and more precise cutting can be performed. .

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of a cutting blade portion in FIG.

FIG. 3 is a front end view of the drill shown in FIG. 1;

FIG. 4 is a sectional view taken along line AA of the drill shown in FIG.

FIG. 5 is a plan view of the throw-away tip.

6 is a cross-sectional view of the chip shown in FIG. 5, taken along line BB.

FIG. 7 is a diagram showing a cutting state by a cutting edge of a drill, wherein (a) is a diagram showing a chip generation state of an inner blade tip;
(B) is a figure which shows the chip generation state of an outer blade tip.

FIG. 8 is a plan view showing a first modification of the indexable insert used in the drill according to the embodiment.

FIG. 9 is a plan view showing a second modified example of the indexable insert used in the drill according to the embodiment.

FIG. 10 is a plan view showing a third modification of the indexable insert used in the drill according to the embodiment.

FIG. 11 is a side view of a conventional drill.

FIG. 12 is a front end view of the drill shown in FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Throw-away type drill 11 Tool body 18, 32, 34, 36 Throw-away tip 18a Outer blade tip 18b Inner blade tip 23, 33 Cutting blade 24 Step 25 First all blade 26, 26 ', 26 "Second cutting blade

Claims (5)

[Claims] 1. A drilling tool provided with a cutting edge provided with a first cutting edge and a second cutting edge via a step so as to protrude toward a tip end side of the tool main body, wherein the drilling tool is close to a rotation axis of the tool main body. A drilling tool, characterized in that the first cutting edge at the set position is provided so as to protrude more distally than the second cutting edge at a position far from the rotation axis. 2. A cutting tool provided with a first cutting edge and a second cutting edge provided on a tip surface of a tool body through a step to a tip side of the tool body, and a throw-away tip is attached. In a throw-away type drilling tool, the first blade at a position close to the rotation axis of the tool main body is provided so as to protrude more distally than the second cutting blade at a position far from the rotation axis. Indexable drilling tool. 3. The indexable insert comprises an outer cutter tip located on the outer peripheral side with respect to the rotation axis of the tool body and an inner cutter tip located on the inner side, and the cutting edge of the inner cutter tip is an outer cutter tip. 3. The indexable drilling tool according to claim 2, wherein the cutting tool protrudes toward the distal end side from the cutting edge. 4. The first cutting edge of the outer cutting tip protrudes distally from the second cutting edge of the inner cutting tip and is retracted proximally from the first cutting edge of the inner cutting tip. The indexable drilling tool according to claim 3, characterized in that: 5. The throw-away drilling tool according to claim 2, wherein the inner cutter tip and the outer cutter tip are the same shape and the same size throw-away insert.