JP2008023607A - Gun drill and drill body attached thereto - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gun drill and a drill body, even if a shank part is broken, eliminating any necessity of disposing the gun drill whole body and capable of highly precisely drilling a hole at a high-speed rotation. <P>SOLUTION: The shank part 2 and a blade part 5 are integrally formed and the drill body 15 is detachably provided with a driver 3, so that the drill body 15 alone can be replaced and the same driver 3 can be used. This constitution can improve the coaxial precision and run-out precision. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gun drill and a drill body attached to the gun drill.

Conventionally, a gun drill has been used when processing a deep hole having a small hole diameter and a long length. In this gun drill, a blade portion is integrally coupled to a distal end of a shank portion, and a driver is integrally coupled to a proximal end by brazing. Also, by providing an oil hole from the driver to the blade part, cutting oil can be supplied to the tip of the deep hole, and chip discharge, work surface friction reduction and cooling are considered (for example, patents) Reference 1).
JP 2004-066391 A

By the way, the conventional gun drill is usually used by clamping a driver to a holder of a gun drill machine.
Here, the diameter of the shank part that can be attached to the holder is standardized in an inch size, and in order to attach a gun drill having a shank part having a diameter smaller than this diameter, a driver is brazed to the base end. However, in such a conventional gun drill, there is a problem that the entire gun drill must be replaced when the shank portion is broken. Conventionally, since the blade portion is brazed to the shank portion, there is a limit to the coaxial accuracy and runout accuracy of the cutting blade in machining that requires high accuracy. And while the gun drill is a small diameter tool used at high speed rotation, the blade and shank are asymmetrical, so depending on the degree of accuracy, the so-called jump rope phenomenon may occur and the blade may shake, resulting in hole machining accuracy. There is a problem that will deteriorate.

  The present invention has been made in consideration of the above circumstances, and it is not necessary to discard the entire gun drill even when the shank portion is broken, and a gun drill capable of cutting a machining hole with high accuracy during high-speed rotation, and A drill body is provided.

In order to solve the above-described problems, the present invention is characterized in that a holding portion is provided at the base end of the shank of a drill body having a blade portion at the tip of the shank, and a driver is detachably attached to the holding portion. And
Therefore, by configuring in this way, even if the shank part breaks, it is possible to use the driver as it is simply by replacing it, and to the same driver, the drill body having a different blade diameter Can also be drilled.

Moreover, in this invention, the said blade part and the said shank of the said drill main body were integrally formed, It is characterized by the above-mentioned.
By comprising in this way, the coaxial precision and runout precision of a drill main body can be improved.

The drill main body of the present invention is a drill main body attached to such a gun drill, wherein the blade portion of the drill main body and the shank are integrally formed.
The drill body constructed in this way can be used by detachably attaching to the driver of the gun drill, and the drill body can be directly attached to a holder of a machining center or the like without using a driver, for example, except for a dedicated gun drill machine. can do.

Thus, according to the present invention, when the shank portion is broken, it can be used again by exchanging only the drill body, and a drill body having a different inch size can be attached to the same driver.
Moreover, since the coaxial accuracy and runout accuracy of the drill body can be improved, the jumping rope phenomenon that occurs during high-speed rotation can be suppressed. Further, the drill body can be applied to a holder such as a machining center other than a gun drill machine which is a dedicated machine.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is an assembly view of a gun drill 1 according to the present embodiment. FIG. 2 is an enlarged sectional view taken along line AA of the drill body in the embodiment of the present invention, and FIG. 3 is a plan view of the drill body in the embodiment of the present invention.
As shown in FIG. 1, the gun drill 1 is composed of a drill body 15 composed of a shank portion 2 and a blade portion 5 integrally formed of cemented carbide, and a steel material (for example, a material is SCM440 and a hardness is HRC40 to 45). And a driver 3.

  A blade portion 5 is integrally formed at the tip of the shank portion 2 via a step portion, and the blade portion 5 has a back taper (for example, 0.10 to 0.15 / 100) on the outer periphery thereof. Thus, by providing the back taper, it is possible to give relief to the feed movement of the gun drill 1. Further, when the boundary portion between the shank portion 2 and the blade portion 5 is brazed as in the conventional structure, a portion where the strength becomes discontinuous is generated in the step portion, but such a portion does not occur and the tool rigidity Therefore, even a gun drill 1 having a small hole diameter can maintain the strength.

  A cutting blade 7 is integrally formed at the tip of the blade portion 5, and when cutting, the gun drill 1 rotates around the shaft core to perform machining while cutting out a machining hole. The cutting edge 7 is formed in a convex V shape having a protruding end at a position away from the axis of the drill body 15 and is a single blade in this embodiment.

Further, as shown in FIG. 2, the blade portion 5 is provided with an oil hole 8 having a substantially oval cross section. The oil hole 8 penetrates the drill body 15 in the axial direction, and high pressure cutting oil is pumped from a cutting oil supply source of a gun drill machine (not shown). By discharging the pumped cutting oil from the oil hole 8 to the front end surface of the blade portion 5, chips are discharged, and friction of the blade portion 5 and the work site of the work material is reduced and cooled.
Here, since the shank part 2 and the blade part 5 are integrally formed of a cemented carbide having a hardness higher than that of the driver 3, the tool rigidity is high. Therefore, the opening area of the oil hole 8 described above can be increased to increase the discharge amount of the cutting oil.

  As shown in FIG. 3, the drill body 15 is formed with a chip discharge groove 4 having a V-shaped cross section along the axial direction from the tip, and chips after cutting are discharged from the machining hole. ing. Therefore, the cross-sectional shape of the drill body 15 is formed in a substantially arc shape as shown in FIG.

  On the other hand, the drill main body 1 is also integrally provided with an outer cylindrical holding part 16 at the base end of the shank part 2 via a taper part. A cutout portion 9 is provided on the outer peripheral wall of the holding portion 16. The notch 9 has a semi-elliptical shape in plan view, and has an inclined portion 9a (for example, an inclination angle C of 2 degrees) that becomes deeper from the proximal end side to the distal end side of the shank portion 2 and the inclined portion 9a. The wall portion 14 extends from the end portion to the outer peripheral wall of the shank portion 2. The wall 14 of the notch 9 is formed perpendicular to the axial direction. The wall portion 14 may be formed so that a direction perpendicular to the axis from the outer peripheral wall is a horizontal plane, and has a small elevation angle α (for example, 2 degrees) with respect to the horizontal plane.

  The driver 3 is a hollow, substantially cylindrical body, and a flat portion 10 is provided by cutting out the central portion of the outer peripheral wall. The flat portion 10 clamps the driver 3 to a holder of a gun drill machine. A drill body 15 is connected to the inside of the driver 3, and a connection hole 11 is provided for pressure-feeding the cutting oil supplied from the gun drill machine to the oil hole 8 described above.

  On the front end side of the driver 3, a screw hole 12 that is opened from the outer peripheral wall of the driver 3 and intersects with the connection hole 11 described above and opens at the inner peripheral wall of the connection hole 11 is provided. Further, the screw hole 12 is formed to have a small depression angle β (for example, 2 degrees) equal to the inclination angle with respect to the axis of the inclined portion 9a toward the rear end side with respect to the horizontal plane. A screw 13 (for example, a flat-head hexagon socket set screw) for fixing the drill body 15 is screwed.

Next, the operation will be described.
As shown in FIG. 1, the base end side of the drill body 15 is inserted into the connecting hole 11 of the driver 3, and the above-described notch 9 of the drill body 15 is disposed at a position facing the screw hole 12 of the driver 3. .
Next, the drill body 15 is connected to the driver 3 by screwing the screw 13 into the screw hole 12. Further, when the screw 13 is screwed, the screw 13 comes into contact with the inclined portion 9a of the notch portion 9. At this time, since the connecting hole 11 of the screw 13 is formed to have a depression angle β equal to the inclination angle C of the inclined portion 9a, the screw 13 abuts perpendicularly to the inclined portion 9a, and the drill body 15 and the driver 3 are securely fixed. The Therefore, the screw 13 is engaged between the inclined portion 9a and the wall portion 14, and vibration caused by resistance force during cutting can be suppressed. Moreover, the driver 3 and the drill main body 15 are more firmly connected by forming the wall portion 14 of the notch 9 at an elevation angle α with respect to the axial direction.

  Therefore, according to the above-described embodiment, by attaching the drill body 15 and the driver 3 in a detachable manner, when the drill body 15 is broken, only the drill body 15 can be replaced and the driver 3 can be used again. It is possible to use drill bodies 15 having different blade diameters.

  Furthermore, by integrally forming the shank portion 2 and the blade portion 5, the coaxial accuracy and runout accuracy are improved, and there is an effect that the jumping rope phenomenon that occurs when the gun drill 1 rotates at high speed can be suppressed. In addition, the structure is simpler than the conventional gun drill in which the blade portion, the shank portion, and the driver are combined by brazing.

In addition, this invention is not restricted to embodiment mentioned above, For example, it can employ | adopt in the following aspects.
First, the present invention can be adopted in a configuration in which a drill body and a driver are detachably attached to a deep hole tool such as a gun reamer, assuming that a gun drill is widely recognized. In the present embodiment, the number of cutting blades formed on the blade portion 5 is described as one blade, but the number of cutting blades may be arbitrary.

  Then, by attaching the holder 16 of the drill body 15 described above to various holders such as a machining center (not shown), only the drill body can be easily used in other machine tools such as a machining center without using the driver 3. It is possible.

It is an assembly top view of the gun drill in an embodiment of the invention. FIG. 4 is an enlarged sectional view taken along line AA in FIGS. 1 and 3 in the embodiment of the present invention. It is a top view of the drill main body in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gun drill 2 ... Shank part 3 ... Driver 5 ... Blade part 15 ... Drill main body 16 ... Holding part

Claims (3)

  A gun drill characterized in that a holding portion is provided at a proximal end of the shank portion of a drill body provided with a blade portion at a tip end of the shank portion, and a driver is detachably attached to the holding portion.   The gun drill according to claim 1, wherein the blade portion and the shank portion of the drill body are integrally formed. It is a drill main body attached to the gun drill of Claim 2, Comprising: The said blade part and the said shank part of the drill main body formed integrally.

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