JPH0631516A - Burnishing drill - Google Patents

Abstract

PURPOSE:To provide a burnishing drill excellent in its drill edge and reamer edge wear resistance, which remarkably enhances the finished hole. CONSTITUTION:In a burnishing drill 1 at the tip of a drill body connected to a cylindrical shank first small dia. parts 13a, 13b and second small dia. parts 14a, 14b of which outer dia. are smaller than the shank are formed. Cubic boron nitride chips 18a, 18b fixed to the tips of the first small dia. parts 13a, 13b have drill edges 30a, 30b while boron nitride chips 20a, 20b fixed to the tips of the second dia. parts 14a, 14b have reamer edges 38a, 38b. Upon drilling, the drilled hole is formed which has a relatively smooth inner circumferential face by drill edges 30a, 30b, and the dia. increasing margin of the drilled hole is cut accurately by the reamer edges 38a, 38b and thereby a finished reamer hole having a further smooth inner circumferential face is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burnishing drill that combines the functions of a drill and a reamer.

[0002]

2. Description of the Related Art Conventionally, as a burnishing drill having a cutting edge for drilling and a cutting edge for reaming in a single tool, diamond, cubic boron nitride, etc. are used for the drill body made of cemented carbide. It is known that a thin plate for a reamer blade is attached. For example, the one with a thin diamond plate attached is used for processing materials such as aluminum alloys,
With the cubic boron nitride thin plate attached, gray cast iron,
Used for processing materials with a relatively high carbon content such as spheroidal graphite cast iron. During machining, a prepared hole is formed with a drill blade made of cemented carbide, and the inner peripheral surface of this prepared hole is ground with a high-hardness reamer blade slightly larger in outer diameter than the drill blade. Therefore, the inner peripheral surface of the finishing hole becomes smooth.

[0003]

However, according to such a conventional burnishing drill, when a relatively high precision is required for the finishing hole, if the surface roughness of the prepared hole formed by the drill blade is large, The blade may not be able to accurately cut the hole diameter expansion allowance, and the precision of the finishing hole may become insufficient. In particular, if the feed speed is relatively high, the precision of the finishing hole is likely to decrease. In addition, when a drill is used for a long period of time, the material of the drill blade and the material of the reamer blade are different, so that there is a problem that the amount of wear tends to vary and cutting stability tends to decrease.

The present invention has been made in order to solve the above problems, and it is a burnishing drill which is improved in wear resistance of a drill blade and a reamer blade, and is capable of greatly improving the accuracy of finishing holes. The purpose is to provide.

[0005]

A burnishing drill according to the present invention for solving the above-mentioned problems includes a drill body connected to a shank and a drill body, which is attached to the tip of the drill body and extends rearward from the center of the tip toward the radially outward direction. A pair of first cutting edges made of a cubic boron nitride thin plate inclined at a first cutting edge angle, and a plane attached to the tip of the drill body and including the drill axis and including the first cutting edges. A cubic boron nitride having a maximum outer diameter larger than the maximum outer diameter of the first cutting edge, the cubic boron nitride being inclined rearward with a second cutting edge angle in a radial direction. And a pair of second cutting blades made of a thin plate.

It is characterized in that the first cutting edge and the second cutting edge are formed by a diamond thin plate instead of the cubic boron nitride thin plate.

[0007]

According to the burnishing drill of the present invention, the prepared hole of the smooth inner peripheral surface formed by the first cutting blade having a relatively high hardness is changed to the smoother inner peripheral surface by the second cutting blade having a high hardness. Finish. Therefore, the centripetal property is improved, and the accuracy of the finishing hole is significantly improved.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. A burnishing drill according to a first embodiment of the present invention is shown in FIGS. As shown in FIG. 2, a burnishing drill 1 used for boring a workpiece made of gray cast iron, spheroidal graphite cast iron or the like is a drill made of a super high alloy in the axial direction of a cylindrical shank 11 made of tool steel or the like. The body 12 is connected. The end 12a of the drill body 12 on the shank 11 side is cut into a V shape, and the connecting portion 11 of the shank 11 is cut.
It is fixed to the groove 11a of b by brazing. Connection part 11b
Is the base 11d and the tongue 11e via the small diameter portion 11c.
It is connected to.

As shown in FIG. 3, the drill body 12 is
A pair of first lands 2a and 2b extending in the axial direction and connected to the shank 11, and a pair of second lands 3a and 3b formed at a position deviated from the first lands 2a and 2b by approximately 90 ° in the circumferential direction. Have. The relief grooves 4, 5 formed between the first lands 2a, 2b and the second lands 3a, 3b are connected to the end 12a of the drill body 12. During drilling, the cutting waste of the work piece is discharged to the outside of the hole through the relief grooves 4 and 5.

First land 2a, 2b and second land 3
The first small diameter portions 13a, 13b having a smaller outer diameter than the maximum outer diameter of the drill body 12 and the second
Small-diameter portions 14a and 14b are provided on the tip side from the step portions 15 and 16. The step portion 15 is formed slightly on the axial tip side with respect to the step portion 16, and is in the drill rotation direction (arrow A shown in FIG. 1).
Direction) The chamfering blade 15a is provided on the front side.

Then, as shown in FIG. 1, the first small-diameter portion 1
3a, 13b and CBN tips 18a, 18b for a drill blade and cubic CBN tips 18a, 18b made of cubic boron nitride (CBN) and CBN tips 20a, 20b for a reamer blade are formed at positions that form the tip outer diameters of the second small diameter portions 14a, 14b. Mounted.
In this case, the CBN chips 18a, 18b and the CBN chips 20a, 20b have the concave grooves 22, 2 formed in the first small diameter portions 13a, 13b and the second small diameter portions 14a, 14b.
4 is brazed and fixed via braiding blades 26 and 28. CBN chips 18a, 18b and CBN
The front end faces of the tips 20a and 20b in the drill rotation direction are connected to the groove faces of the relief grooves 4 and 5.

As shown in FIG. 5, the CBN chip 18a,
The outer peripheral end surface 18c of the arcuate cross section of 18b has the first small diameter portion 1
It is connected to the relief surface 41 of 3a, 13b. The arcuate surface 45 formed at the outermost diameter ends of the first small diameter portions 13a and 13b is
The CBN chips 18a and 18b are formed slightly radially outward of the outer peripheral end surfaces 18c and are continuous with the relief surface 41.

As shown in FIG. 7, the CBN tips 18a and 18b are flat plates having a predetermined thickness L ₁ and a length l ₁ and have a cutting edge angle α with respect to the drill axis at the peripheral end. It has linear drill blades 30a and 30b. Cutting edge angle α
Is set to, for example, 45 ° to 90 °. Drill blade 30
Curved surfaces 32 are formed at corners on the opposite sides of a and 30b so as to make it difficult to form a gap when fitting into the groove 22.

As shown in FIG. 8, the CBN chip 18a,
CBN chip 20 formed with a width of about half of 18b
Each of a and 20b has a thickness L ₂ and a length l ₂ which are approximately the same as the thickness L ₁ and has a reamer having a predetermined cutting edge angle β with respect to the drill axis at a corner facing the curved surface 36. Blade 38
a and 38b. The cutting edge angle β of the reamer blades 38a, 38b is, for example, 10 ° to 45 ° so as to improve cutting stability.
It is set to a degree. The CBN chips 18a, 18b
The length l ₁ of the CBN tips 20a and 20b can be changed within the range of the axial length of the first small diameter portions 13a and 13b according to the cutting conditions.

Further, as shown in FIG. 6, the CBN chip 2
The outer peripheral end surface 20c having an arcuate cross section of 0a, 20b is continuous with the relief surface 42 of the second small diameter portion 14a, 14b. The arcuate surface 46 formed at the outermost diameter ends of the second small diameter portions 14a, 14b is
It is formed so as to have an outer diameter substantially the same as that of the outer peripheral end surface 20c. The notch groove 4 is provided between the outer peripheral end surface 20c and the arc surface 46.
7 are formed.

Here, the CBN chips 20a and 20b are
As shown in FIG. 4, the outermost radial ends of the reamer blades 38a, 38b are arranged so as to extend radially outward by a distance δ from the outermost radial ends of the drill blades 30a, 30b. As a result, the holes drilled by the drill blades 30a, 30b are further smoothly finished by the reamer blades 38a, 38b. Further, the reaming blades 38a and 38b can set the cutting edge angle β to a relatively acute angle, and the initial clinging becomes good.

From the tip of the drill body 12 farthest from the shank 11, the drill blades 40a, 40b shown in FIG. 2 are formed with a cutting edge angle α so as to incline on a straight line as it goes radially outward, and a CBN tip. 18a, 18
It is connected to the drill blades 30a and 30b of b. As shown in FIG. 1, on the rear side in the rotation direction of the drill blades 40a and 40b,
A first inclined surface 43 and a second inclined surface 44 are formed which incline toward the shank 11 in the radially outward direction. A relief portion 48 is formed at the base of the drill blades 40a, 40b that escapes toward the center of the tip toward the shank 11, and a relief groove 4 is formed in the direction in which the relief portion 48 extends toward the shank 11 side.

When the burnishing drill 1 constructed as described above is rotated in the direction of arrow A shown in FIG. 1, first, the workpiece is scraped off by the drill blades 40a, 40b and the drill blades 30a, 30b, so that the inner circumference is relatively smooth. A drill hole with a face is drilled. Then, the hole diameter expansion allowance of this drill hole is accurately scraped off by the reamer blades 38a, 38b,
Finish with a reamed hole with a smoother inner surface.

According to the burnishing drill 1, since the centers of rotation of the drill blades 40a, 40b, the drill blades 30a, 30b, and the reamer blades 38a, 38b are coincident with each other, the centripetal property at the time of drilling is improved and the cutting stability is improved. Is greatly increased. Further, since the drill blades 30a, 30b and the reamer blades 38a, 38b have good wear resistance, a relatively stable drill life is secured even if the rotation speed (cutting speed) and the feed speed are high.

Next, a second embodiment of the present invention is shown in FIG.
The burnishing drill 50 according to the second embodiment is for drilling a workpiece made of an aluminum material or the like, and has diamond tips 52 instead of CBN tips for the drill blade and reamer blade.
a, 52b and diamond tips 54a, 54b are used. Diamond tip 52 when drilling
A pilot hole is formed by the drill blades 55a and 55b of a and 52b, and the reamer blade 56 of the diamond tips 54a and 54b is formed.
The inner peripheral surface of the prepared hole is smoothly finished with a and 56b.
Since the other components are substantially the same as those in the first embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

[0021]

As described above, according to the burnishing drill of the present invention, since the drill blade and the reaming blade are formed of a thin plate of cubic boron nitride or diamond having a relatively high hardness, wear resistance and The durability is improved, and the precision of the finishing hole can be significantly improved.

[Brief description of drawings]

FIG. 1 is a front view showing a burnishing drill according to a first embodiment of the present invention.

FIG. 2 is a side view showing a burnishing drill according to a first embodiment of the present invention.

FIG. 3 is a sectional view taken along line AA of the burnishing drill shown in FIG.

FIG. 4 is a diagram showing the relationship between the maximum outer diameter of the first cutting edge and the maximum outer diameter of the second cutting edge according to the first embodiment of the present invention.

FIG. 5A is a partially enlarged front view showing a cubic boron nitride chip used for the drill blade of the first embodiment of the present invention,
(B) is a side view thereof.

FIG. 6 (A) is a partially enlarged front view showing a cubic boron nitride chip used for the reamer blade of the first embodiment of the present invention,
(B) is a side view thereof.

FIG. 7A is a plan view showing a cubic boron nitride chip used for the drill blade of the first embodiment of the present invention, and FIG. 7B is a side view thereof.

8A is a plan view showing a cubic boron nitride chip used for a reamer blade according to the first embodiment of the present invention, and FIG. 8B is a side view thereof.

FIG. 9 is a front view showing a burnishing drill according to a second embodiment of the present invention.

[Explanation of symbols]

1 Vanishing drill 11 Shank 12 Drill body 18a, 18b CBN tip (cubic boron nitride thin plate) 20a, 20b CBN tip (cubic boron nitride thin plate) 30a, 30b Drill blade (first cutting edge) 38a, 38b Reamer Blade (second cutting edge) 52a, 52b Diamond tip (diamond thin plate) 54a, 54b Diamond tip (diamond thin plate)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Fukui 26 Hirako Yoshiwara-cho, Toyota-shi, Aichi Fuji Seiko Co., Ltd. 72) Inventor Manabu Shimizu 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (2)

[Claims] 1. A drill body connected to a shank, and a cubic boron nitride thin plate that is attached to the tip of this drill body and inclines rearward with a first cutting edge angle as going radially outward from the center of the tip. A pair of first cutting blades, provided on a tip of the drill body, provided in a plane that includes a drill axis and intersects a plane that includes the first cutting blades, and a maximum outer diameter of the first cutting blades; And a pair of second cutting blades made of a cubic boron nitride thin plate which has a maximum outer diameter larger than the diameter and inclines with a second cutting blade angle toward the outer radial direction. A burnishing drill. 2. The burnishing drill according to claim 1, wherein the first cutting edge and the second cutting edge are formed of a diamond thin plate instead of the cubic boron nitride thin plate.