JP2003275910A - Drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill free of breakage or the like by preventing occurrence of chip clogging even in the drill with a long cutting blade portion 2. <P>SOLUTION: This drill is provided with a chip evacuation slot 5 formed on an outer periphery of a tip part of a drill body 1 and a cutting edge 7 formed on an intersectional ridge line part between a rake face formed on an inner peripheral surface 6 of the chip evacuation slot 5 and a tip flank 4 of the drill body 1. The drill body 1 is coated with a hard film 11 on its surface of the tip part, and the inner peripheral surface 6 of the chip evacuation slot 5 is subjected to polish processing after being coated with the hard film 11. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly includes a chip discharge groove formed on the outer periphery of the tip of a drill body, and a cutting blade provided on the tip of the inner peripheral surface of the chip discharge groove facing the direction of rotation of the drill. The present invention relates to a drill used for drilling a workpiece made of a metal material.

[0002]

2. Description of the Related Art As such a drill, the tip side of a substantially cylindrical drill body which is rotated around the axis in the drill rotation direction is used as a cutting edge portion, and a pair of cutting edges is provided on the outer periphery of the cutting edge portion. A spiral that twists backward in the direction of rotation of the drill around the axis as it goes from the tip end surface of the cutting edge part, that is, the tip flank of the drill body toward the rear end side, so that the chip discharge grooves of are symmetrical with respect to the axis. So-called two-flute solid drill in which the cutting edge is formed in the ridge line intersecting with the tip flank on the tip side of the inner peripheral surface of the chip discharge groove facing the drill rotation direction. It has been known. Therefore, in such a solid drill, the tip side of the portion of the inner circumferential surface of the chip discharge groove facing the drill rotation direction is the rake face of this cutting blade, and the chips generated by the cutting blade are the chip discharge groove from this rake face. While slidably contacting the inner peripheral surface of the chip, the chip discharge groove is twisted so that it is sent out to the rear end side and discharged. Further, in such a drill, a hard coating such as TiN or TiCN is coated on the entire surface of the cutting edge portion in order to improve the wear resistance of the drill body.

[0003]

By the way, in recent years, in such a solid drill, the length of the cutting edge portion is 10 × D to 20 × D with respect to the outer diameter D of the cutting edge, depending on the case. With the use of up to 25 × D, deep holes that were conventionally performed by gun drills are now more often performed by such solid drills in order to improve machining efficiency. With a drill that has a long cutting edge length and performs deep hole drilling, there is a problem that chips generated by the cutting blade are also discharged through the chip discharging groove for a long length, which easily causes chip clogging. .
Then, in the drill coated with a hard coating on the entire surface of the cutting edge portion as described above, where the hard coating is also coated over the entire length of the cutting edge portion on the inner peripheral surface of the chip discharging groove, Such a hard coating has a relatively rough surface roughness of 2 to 4 μm, and the chips are fed to the rear end side while slidingly contacting the inner peripheral surface of the chip discharge groove coated with such a hard coating, thereby cutting chips. Ejection resistance increases and chip clogging becomes more likely to occur. On the other hand, since the rigidity and strength of the drill body tends to be impaired due to the increased length of the cutting edge portion, in the above-described drill, breakage of the drill due to clogging of chips may frequently occur. .

The present invention has been made under such a background, and even in the drill having a long cutting edge portion as described above,
It is an object of the present invention to provide a drill that prevents clogging of chips and prevents breakage and the like.

[0005]

In order to solve the above problems and to achieve such an object, the present invention forms a chip discharge groove on the outer periphery of the tip of a drill body, and the inner circumference of the chip discharge groove. While forming a cutting edge on the ridge portion where the rake face formed on the surface and the tip flank of the drill body, the surface of the tip portion of the drill body is coated with a hard coating, and further the chip discharge groove The inner peripheral surface is characterized by being coated with this hard coating and then subjected to polishing. Therefore,
In such a drill, after coating a hard coating with rough surface roughness, the inner peripheral surface of the chip discharge groove is polished and the surface is made smooth, so frictional resistance when the chips are in sliding contact is small. Since it is smoothly pushed to the rear end side and discharged, clogging of chips does not occur.

Here, such polishing is performed by polishing the inner peripheral surface of the chip discharge groove with a brush coated with an abrasive such as diamond paste. The chip discharge groove thus polished is thus processed. The surface roughness of the inner peripheral surface is in the range of 0.5 to 1.5 μm in the extending direction of the chip discharge groove, and in the range of 1.0 to 2.0 μm in the peripheral direction of the inner peripheral surface. Is desirable.
This is because if the surface roughness is larger than the above range, the friction reducing effect due to the sliding contact of chips is small, and conversely, if the surface roughness is smaller than this range, it takes a lot of time and labor to reduce the surface roughness. is there. Further, the surface roughness of the inner peripheral surface of the chip discharge groove that has been subjected to polishing is such that the surface roughness measured in the extending direction of the chip discharge groove is more than the surface roughness measured in the circumferential direction of the inner peripheral surface. It is also desirable to be smooth.

[0007]

1 to 3 show an embodiment of the present invention. In the drill of the present embodiment, the drill body 1 is made of a hard material such as cemented carbide and has a substantially cylindrical shape centered on the axis O, and its tip side (left side in FIGS. 1 and 2) is the cutting edge portion 2. The rear end side (right side in FIG. 1) is a shank portion 3.
Then, on the outer periphery of the cutting edge portion 2, from the tip flank 4 of the tip of the drill body 1 toward the rear end side to just before the shank portion 3, as it goes backward in the axis O direction, the rear side in the drill rotation direction T A pair of chip discharge grooves 5 and 5 spirally twisted to the side are formed so as to be symmetrical with respect to the axis O, and the tip end of the inner peripheral surface 6 of the chip discharge groove 5 is in the drill rotation direction T.
A portion facing the side is a rake face, and a cutting edge 7 is formed at a ridge line portion where the rake face and the tip flank 4 intersect.

In the present embodiment, the length of the cutting edge portion 2 in the direction of the axis O is relative to the diameter of the circle formed by the outer peripheral end of the cutting edge 7 around the axis O, that is, the outer diameter D of the cutting edge 7. It is set to 10 × D or more, and in some cases 20 × D or more, or 25 × D or more. Furthermore, in the drill body 1, a pair of cutting oil supply paths 8 and 8 are provided from the rear end toward the front end.
However, it is formed in a spiral shape so as to avoid the chip discharge grooves 5 and 5, and is opened to the tip flank 4.

Further, on the outer peripheral surface between the chip discharge grooves 5 and 5 in the circumferential direction of the cutting edge portion 2, at a ridge line portion intersecting with the chip discharge groove 5 which is spirally twisted on the drill rotation direction T side. , A margin portion 9 is formed. The outer peripheral surface of the margin portion 9 has an arcuate cross-section with an outer diameter equal to the outer diameter D of the cutting blade 7, and is provided in the chip discharge groove 5 over the entire length of the cutting blade portion 2 with a small constant width in the circumferential direction. It is extended along. Further, on the rear side of the margin portion 9 in the drill rotation direction T,
The one-step drill body 1 with respect to the outer peripheral surface of the margin portion 9
An outer peripheral flank 10 having a small outer diameter and having an arcuate cross section is formed so as to recede toward the inner peripheral side. The cutting edge 6, the margin portion 9 and the outer peripheral flank 10 are also formed in a pair symmetrically with respect to the axis O, similarly to the chip discharge grooves 5 and 5. In addition, these margin portions 9 and outer flanks 1
A back taper may be given to 0.

Further, a hard coating 11 is coated on the surface of the cutting edge portion 2 thus constructed over the entire length of the cutting edge portion 2. As the hard coating 11, for example, Ti
Coating with one or more of C, TiN, TiCN, and TiAlN can be mentioned, and the surface roughness is 2 to 4 μm as described above in the state of being coated. Then, of the surfaces of the cutting edge portion 2 coated with the hard coating 11 in this way, the inner peripheral surface 6 of the chip discharge groove 5 is coated with a paste containing, for example, diamond particles on a brush to form the inner peripheral surface 6. The surface of the inner peripheral surface 6 is coated with a hard coating 11 by polishing the inner peripheral surface 6 by polishing or polishing the inner peripheral surface 6 as shown in FIG. 1 to FIG. It is smaller than the surface roughness of the hard coating 11 on the outer peripheral surface of the tip flank 4 or the margin portion 9 as it is, or on the outer peripheral flank 10, that is, it is made smooth.

Moreover, in this embodiment, the surface roughness of the inner peripheral surface 6 of the chip discharge groove 5 is measured in the direction in which the chip discharge groove 5 twisted in a spiral extends, that is, in the direction along the spiral. The roughness is smaller than the surface roughness measured along the circumferential direction of the inner peripheral surface 6, that is, the direction orthogonal to the spiral, that is, smoother. Further, the surface roughness of the inner peripheral surface 6 of the chip discharge groove 5 thus polished is in the range of 0.5 to 1.5 μm in the direction in which the chip discharge groove 5 extends, and the circumference of the inner peripheral surface 6 is also increased. In the direction, the range is 1.0 to 2.0 μm. In order to make the surface roughness in the direction in which the chip discharge groove 5 extends smaller and smoother than the circumferential direction of the inner peripheral surface 6 as described above, for example, the brush during polishing is mainly used along the chip discharge groove 5. The inner peripheral surface 6 may be polished by moving it.

Therefore, in the thus constructed drill, the chips generated by the cutting blade 7 are discharged while slidingly contacting the inner peripheral surface 6 of the polished chip discharge groove 5, so that the friction resistance is increased. It is possible to smoothly discharge chips from the processed hole without causing chip clogging. Therefore, even when the deep hole as described above is processed, the drill body 1 is not broken due to the clogging of the chips, and reliable and stable drilling can be performed. Further, since the resistance when discharging chips is small as described above, the drill having the above-described configuration can reduce the rotational driving force of the drill body 1 during drilling, and thus more stable drilling of deep holes. Can be encouraged. Moreover, even though it is polished, since the inner peripheral surface 6 of the chip discharge groove 5 is covered with the hard coating 11 as described above, it is less likely to wear due to sliding contact of chips, and the polishing process is not performed. Since the hard coating 11 that remains coated remains on the surface of the cutting edge portion 2 other than the inner peripheral surface 6 of the chip discharge groove 5 that has been cut,
It is possible to provide a drill having high wear resistance as in the past.

Further, in this embodiment, the surface roughness of the inner peripheral surface 6 of the chip discharge groove 5 subjected to this polishing is
0.5 ~ in the direction in which the chip discharge groove extends spirally
It is set to a range of 1.5 μm and is set to a range of 1.0 to 2.0 μm in the circumferential direction of the inner peripheral surface 6, and the former is smoother than the latter, that is, the surface roughness is small. Has been done. Therefore, even in the chip discharge groove 5 that has been subjected to the polishing process, the chips flow out while being guided in the direction in which the chip discharge groove 5 extends rather than the circumferential direction of the inner peripheral surface 6. Therefore, according to the drill of the present embodiment, not only when the chip-shaped chips are generated depending on the material type of the work piece but also when the chip-shaped chips are generated, the chips in the chip discharge groove 5 are removed. It is possible to surely discharge it without retaining it in the processed hole. Incidentally, these surface roughness is larger than the above range,
That is, if the surface is rough, it may not be possible to obtain the good chip discharge performance as described above. On the other hand, it takes a lot of labor and time to finish the inner peripheral surface 6 smoothly so that the surface roughness becomes smaller than this range. However, there is a possibility that the chip discharging property will not be significantly improved and the efficiency may be rather reduced. Therefore, the above range is preferable.

[0014]

As described above, according to the present invention,
Even if you are processing a deep hole due to the long cutting edge,
It is possible to improve the chip discharge performance while preventing wear of the cutting edge portion, prevent a situation where the drill body is broken due to clogging of chips, and perform smooth and stable drilling.

[Brief description of drawings]

FIG. 1 is a side view of a drill body 1 showing an embodiment of the present invention.

FIG. 2 is an enlarged side view of a tip side of a cutting blade portion 2 of the embodiment shown in FIG.

FIG. 3 is an enlarged front view of the embodiment shown in FIG. 1 seen from the tip side.

[Explanation of symbols]

1 drill body 2 cutting edge 4 Tip flank 5 Chip discharge groove 6 Inner peripheral surface of chip discharge groove 4 7 cutting edge 11 Hard coating O Drill body 1 axis T drill rotation direction D Cutting edge 7 outer diameter

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoji Takiguchi             1528, Nakashinden, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture             Address Mitsubishi Materials Corporation Gifu Factory             Within (72) Inventor Masayuki Mabuchi             1528, Nakashinden, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture             Address Mitsubishi Materials Corporation Gifu Factory             Within F term (reference) 3C037 CC06

Claims (4)

[Claims] 1. A chip discharge groove is formed on the outer periphery of the tip of the drill body, and a cutting edge is provided at the ridge line intersecting with the rake face formed on the inner peripheral surface of the chip discharge groove and the flank of the tip of the drill body. Along with the formation, the surface of the tip of the drill body is coated with a hard coating, and further, the inner peripheral surface of the chip discharge groove is coated with the hard coating and then polished. Characteristic drill. 2. The surface roughness of the inner circumferential surface of the polished chip discharge groove is in the range of 0.5 to 1.5 μm in the extending direction of the chip discharge groove. The drill according to claim 1. 3. The surface roughness of the inner peripheral surface of the chip discharge groove subjected to the polishing is in the range of 1.0 to 2.0 μm in the circumferential direction of the inner peripheral surface. The drill according to claim 1 or claim 2. 4. The surface roughness of the inner peripheral surface of the polished chip discharge groove is measured in the extending direction of the chip discharge groove, and is measured in the circumferential direction of the inner peripheral surface. The drill according to any one of claims 1 to 3, wherein the drill has a smoother surface roughness.