JP2001009616A - Extra-high pressure sintered body brazed drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extra-high pressure sintered body brazed drill low in a cost and excellent in cutting quality. SOLUTION: A pair of sheet-shaped cutting edge tips 16 approximately in a pentagonal shape is formed such that a tip material formed that a multicrystal diamond sintered body 12 (an oblique line part) is integrally sintered at a pedestal 24 of cemented carbide at an extra-high pressure is sliced in the direction of thickness. One end face forming a face is inclined and overlapped in an opposite direction back to back and inserted in the mounting groove 20 of a drill body 14 for brazing. This constitution brings all of the face angles αof a pair of cutting edges 12a consisting of the respective ridges of a multicrystal diamond sintered body 12 into a positive state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill, and more particularly to an improvement in an ultra-high pressure sintered body brazing drill in which a cutting edge tip of an ultra-high pressure sintered body is brazed to a tip end portion.

[0002]

2. Description of the Related Art A cutting edge tip made of an ultra-high pressure sintered body obtained by sintering a super hard non-alloy such as cubic boron nitride (CBN) or polycrystalline diamond (PCD) at an ultra high pressure is integrated with a tip of a drill body. Japanese Patent Laid-Open Nos. 6-206111 and 63-63111 disclose an ultra-high pressure soldered brazing drill in which the ridges at the corners of the ultra-high pressure sintered body function as cutting edges.
No. 8309, for example. Such an ultra-high pressure sintered body brazing drill is excellent in wear resistance, and thus is suitably used for drilling difficult-to-cut materials such as MMC such as an aluminum alloy containing SiC.

[0003]

However, in such a conventional ultrahigh-pressure sintered compact brazing drill, the cutting edge tip is composed of only the ultrahigh-pressure sintered compact, or the ultrahigh-pressure sintered compact is mounted on a cemented carbide pedestal. Since the compacts are stacked and brazed in such a manner that the surface of the ultrahigh-pressure sintered body becomes a rake face, there is a problem that the amount of the ultrahigh-pressure sintered body is large in any case and the cost is increased. . In addition, such a cutting edge chip is mounted so that the rake face is substantially parallel to the axis of the tool, and the rake angle of the cutting edge is substantially 0 °, so that the sharpness is poor, and the tool life and finished surface roughness are reduced. There was a problem of being damaged.

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ultra-high pressure sintered compact brazing drill which is inexpensive and has excellent sharpness.

[0005]

In order to achieve the above object, a first aspect of the present invention is to provide a cutting tool having an ultra-high pressure sintered body integrally brazed to the tip of a drill body, An ultrahigh-pressure sintered body brazing drill in which a ridgeline of a corner of a body functions as a cutting edge, wherein the cutting edge tip is formed by integrally integrating the ultrahigh-pressure sintered body with a predetermined thickness on a cemented carbide pedestal. It has a thin plate shape obtained by slicing a chip material sintered at an ultra-high pressure in the thickness direction, the surface side of the ultra-high pressure sintered body in the chip material becomes a flank surface, and one sliced side of the chip material is a rake surface. And the cutting edge is provided with a positive rake angle.

According to a second aspect of the present invention, there is provided the ultrahigh-pressure sintered compact brazing drill according to the first aspect of the present invention, wherein (a) the cutting edge tip has a substantially isosceles-shaped portion corresponding to the shape of the drill tip. The ultra-high pressure sintered body is provided along one of two sides of the portion, (b) at the tip of the drill body,
A mounting groove having a width approximately twice as large as the slice width of the cutting edge chip is provided so as to intersect with the axis, and the cutting edge is arranged so that the ultrahigh-pressure sintered body is positioned symmetrically with respect to the axis. It is characterized in that two chips are stacked in opposite directions, inserted into the mounting groove and brazed.

A third invention is the ultrahigh pressure sintered compact brazing drill according to the first invention or the second invention, wherein the thickness of the cutting edge linearly decreases as the cutting edge tip is separated from the ultrahigh pressure sintered compact. Thus, the one end face serving as a rake face is inclined, and the positive rake angle is provided by the inclination of the one end face.

[0008]

In such an ultra-high pressure sintered compact brazing drill, a thin plate shape obtained by slicing a chip material obtained by sintering an ultra-high pressure sintered compact at an ultra-high pressure integrally with a pedestal of a cemented carbide in the thickness direction is used. Since the surface of the ultrahigh-pressure sintered body in the chip material is a flank and the sliced one end side is a rake face, the surface of the ultrahigh-pressure sintered body is Compared with the case of brazing to form a rake face, the required amount of the ultra-high pressure sintered body is reduced, and the manufacturing cost is reduced. In the case of a drill, corner wear and cutting edge wear, particularly at the outer periphery of the cutting edge, pose a problem.If an ultra-high pressure sintered body is provided with a predetermined thickness, the entire rake face is not an ultra high pressure sintered body. However, there is no significant effect on tool life. Further, since the cutting edge is provided with a positive rake angle, excellent sharpness can be obtained, and tool life and finished surface roughness are improved.

In the second invention, two cutting blades having the same shape are stacked in the opposite direction and are brazed to the mounting groove of the drill body, and the two cutting blades are symmetrically inclined with respect to the axis. Since the blades can be provided at the same time, the drill can be configured simply and inexpensively as compared with, for example, a case where two cutting edge tips are separately brazed at symmetrical positions with respect to the axis. In addition, since each cutting edge tip is provided with an ultra-high pressure sintered body beyond the center of the drill tip according to the thickness of the ultra-high pressure sintered body, the wear resistance at the center of the tip is improved and The service life is further improved.

[0010] In the third invention, one end surface of the cutting edge tip is inclined so that the plate thickness becomes linearly thinner as the distance from the ultrahigh-pressure sintered body increases, and a positive rake angle is provided by the inclination of the one end surface. Therefore, a cutting edge tip having an angle corresponding to the rake angle can be easily obtained by wire electric discharge machining or the like.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The ultrahigh pressure sintered compact brazing drill of the present invention is suitably used for drilling difficult-to-cut materials, but is also applicable to drilling of other materials which are relatively easy to cut. Of course, it can be used. INDUSTRIAL APPLICABILITY The present invention can be applied to various drills such as a twist drill in which a chip discharge groove is twisted with respect to an axis, and a straight blade drill in which a chip discharge groove is parallel to the axis. The ultra-high pressure sintered body is, for example, cubic boron nitride (CBN)
It is obtained by sintering a super-hard non-alloy such as polycrystalline diamond (PCD) at an ultra-high pressure. What is called a diamond compact is also an example of an ultra-high pressure sintered body. As the material of the drill body, a cemented carbide is preferably used, but other materials such as high-speed tool steel can also be used.

It is desirable that the thickness of the ultra-high pressure sintered body integrally sintered at an ultra-high pressure on the cemented carbide pedestal be as thin as possible within a range in which desired effects such as wear resistance can be obtained.
Depending on the type of ultra-high pressure sintered body, for example, 0.3
A range of about mm to 5.0 mm is appropriate, and a range of about 0.5 mm to 2.0 mm is preferable. It is better to be as thin as possible for cost reduction, but 0.3mm
If the thickness becomes smaller, there is a possibility that effects such as wear resistance of the ultrahigh-pressure sintered body cannot be sufficiently obtained. In some cases, the flank surface such as the second surface is processed on the ultrahigh-pressure sintered body. In this case, it is necessary to set the thickness in consideration of the processing allowance.

The thickness of the cutting edge tip, that is, the slice width, is desirably as thin as possible within a range in which a predetermined strength and flank wear resistance can be obtained, for example, 0.3 mm.
It is appropriate that the thickness is in the range of about 4.0 mm to about 4.0 mm.
A range of about mm to 2.0 mm is good. When the rake angle is provided by inclining one end surface, it is desirable to set the slice width in consideration of the minimum plate thickness after the incline processing. When slicing the chip material, one end face can be inclined.

It is preferable that the drill body is provided with a mounting seat for backing up the cutting edge tip to the ultrahigh-pressure sintered body. The mounting seat may be a mounting groove that intersects the axis as in the second invention, for example.
When the center of the drill tip is not included, the recess may be a shallow recess provided substantially perpendicular to the cutting rotation direction of the drill. In the second invention, two cutting edge tips are mounted on the drill body in an overlapping manner in the opposite direction. However, when the center portion of the drill tip is not included, a pair of cutting edge tips are symmetrically arranged with respect to the axis. What is necessary is just to make brazing separately. The present invention is also applicable to a single-edged drill.

The rake angle of the cutting edge (the inclination angle of the rake face with respect to the direction parallel to the axis; the rake angle in the axial direction) may be larger than 0 °, and is appropriately determined within a range of about 20 ° or less. In order to obtain sufficient sharpness, about 3 ° or more is desirable. In the case of a twist drill, it is desirable to set the angle substantially equal to or smaller than the twist angle of the chip discharge groove. The rake angle is, for example, 3rd
The cutting edge tip can be provided by linearly inclining one end face of the cutting edge tip as in the invention, but the cutting edge tip having a constant plate thickness (slice width) is inclined with respect to the axis to be brazed to the drill body. In this way, a predetermined rake angle can be provided, or a predetermined rake can be provided on the cutting edge by providing a concave groove having a smoothly curved bottom cross-section like a chip breaker along the cutting edge. Corners can also be provided. When the one end face is inclined linearly as in the third invention, a predetermined rake angle can be provided simultaneously with a positive rake angle depending on the mounting posture of the cutting edge tip.

The cutting edge tip according to the second aspect of the present invention is configured substantially symmetrically with respect to a center line passing through the apex of the chevron, and may be composed of only an isosceles triangular chevron. A pentagonal portion having a square portion having a width substantially equal to the diameter of the drill continuously and preferably having a pentagonal shape is preferably used. An angled portion may be bent in a shape of a letter along two sides of an isosceles triangle. In practicing another invention, the shape of the cutting edge tip is appropriately determined.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIGS. 1A and 1B are views showing a tip portion of a twist drill 10 to which the present invention is applied. FIG. 1A is a plan view seen from the tip side, FIG. 1B is a front view seen from a direction perpendicular to the axis, and FIG. )
FIG. 5B is a right side view of FIG. 5B, and a hatched portion indicates an ultra-high pressure sintered body, in this embodiment, a polycrystalline diamond sintered body 12.
2 and FIGS. 5 to 8 also indicate the ultrahigh-pressure sintered body. The twist drill 10 has a diameter of 6 mm and includes a drill body 14 made of cemented carbide and a pair of cutting edge tips 16 brazed to the tip of the drill body 14 with a silver braze. It is configured. The drill body 14 has a pair of chip discharge grooves 1 with a twist angle of about 20 °.
1 and a mounting groove 20 having a width approximately twice as large as the thickness of the cutting edge tip 16 is provided at the tip end in the groove length direction as shown in FIGS. 1 (a) and 1 (b). It is provided so as to intersect at right angles with the axis and to be substantially parallel to the axis in the groove depth direction as shown in FIG.
A pair of cutting edge tips 16 are arranged in the same direction in the opposite direction.

FIG. 4 shows the drill body 14 in a state before the cutting edge chip 16 is mounted. The mounting groove 20 partially intersects the chip discharge groove 18 and
Notch 22 is provided such that the portion functioning as cutting edge 12a and the rake face is exposed. The chip discharge groove 18 is formed by grinding using a diamond grindstone, and the mounting groove 20 is formed by wire cut electric discharge machining. The mounting groove 20 can also be formed by grinding with a diamond grindstone.

As shown in FIG. 2, the cutting edge tip 16 has an isosceles triangular chevron 1 corresponding to the shape of the drill tip.
6a and a quadrangular portion 16b provided on the base of the isosceles triangle and having a width substantially equal to the diameter of the drill, forming a pentagon as a whole. The angle of the apex of the chevron 16a is set to, for example, about 118 ° corresponding to the tip angle of the twist drill 10. As shown in FIG. 3 (a), this cutting edge chip 16 is placed on a pedestal 24 of cemented carbide and sintered integrally at an ultra-high pressure by pressing to form a predetermined surface of the pedestal 24. After producing a columnar chip material 26 integrally having a polycrystalline diamond sintered body 12 having a thickness d of thickness d, the thickness is set to a constant slice width (the maximum plate thickness of the cutting edge chip 16) t as shown by a dashed line. 3 (b), and sliced in such a manner that the polycrystalline diamond sintered body 12 is positioned along one of the two sides of the chevron 16a as shown in FIG. 3 (b). The thickness d of the polycrystalline diamond sintered body 12 is about 0.8 mm, the thickness (slice width) t of the cutting edge tip 16 is about 1.0 mm, and the thickness of the cemented carbide pedestal 24 is a pentagon. It is determined so that the cutting edge tip 16 can be taken out. The cutting of the chip material 26 is preferably performed by wire cut electric discharge machining.

As is clear from FIGS. 2A and 2C, one end face of the cutting edge tip 16, that is, the drill body 14 is provided.
The end face 16c on the side that functions as a rake face in the state of attachment to the
(the lower side in (b)), in other words, as the distance from the polycrystalline diamond sintered body 12 increases, the plate thickness is inclined so as to become linearly thinner. The cutting edge 12a, which is the ridgeline of the corner of the united body 12, is formed at an acute angle. The tilting of the one end surface 16 is performed by wire cut electric discharge machining or grinding by a diamond grindstone. Therefore, when the opposite end face 16 d is attached to the drill body 14 in a posture parallel to the axis, the cutting edge 12 a
Is provided with a positive rake angle α. This rake angle, that is, the inclination angle (axial rake angle) α of the one end face 16c with respect to the direction parallel to the axis is smaller than the twist angle of the chip discharge groove 18, and is set to about 10 ° in this embodiment. . Both side walls of the mounting groove 20 are inclined at the same angle with respect to a plane parallel to the axis corresponding to the inclination of the one end face 16c, and the pair of cutting edge tips 16 are back-to-back, that is, the end faces 16d are It is inserted into the mounting groove 20 in a state of being in close contact. The cutting edge 12a has one end face 16c and the surface 12f of the polycrystalline diamond sintered body 12 in the state of the chip material 26 (see FIGS. 3A and 3B).
The surface 12f of the polycrystalline diamond sintered body 12 is located on the flank side.

FIG. 5 shows a state in which a pair of cutting edge tips 16 are overlapped in the opposite direction, inserted into the mounting groove 20 of the drill body 14 in FIG. 4, and brought into brazing. After a pair of cutting edges 16 are brazed to the drill body 14 as shown in FIG. 5, the chip discharge grooves 18 including the cutting edges 16 are ground by a diamond grindstone, and the tip second and third end surfaces are ground. Grinding of the surface and the thinning is also performed using a diamond grindstone.

The twist drill 10 according to the present embodiment as described above.
According to this, a thin plate-shaped cutting edge 16 obtained by slicing a chip material 26 obtained by integrally sintering a polycrystalline diamond sintered body 12 at an ultra-high pressure on a cemented carbide pedestal 24 in a thickness direction is used. 26, the surface 12f side is a flank surface and the sliced one end surface 16c side is brazed in a position of a rake surface. In comparison with polycrystalline diamond sintered body 1
2, the required amount is reduced, and the manufacturing cost is reduced. In the case of a drill, corner wear and cutting edge wear, particularly at the outer periphery of the cutting edge, pose a problem. Therefore, if the polycrystalline diamond sintered body 12 is provided with a predetermined thickness, the entire rake face is made of the polycrystalline diamond sintered body. Even if it is not 12, the tool life is not significantly affected. Further, since the cutting edge 12a is provided with a positive rake angle α, excellent sharpness can be obtained, and tool life and finished surface roughness are improved.

Further, in this embodiment, only two cutting edge tips 16 of the same shape are piled up in the opposite direction and are brazed to the mounting groove 20 of the drill body 14, but are inclined symmetrically with respect to the axis. Since two cutting edges 12a can be provided at the same time, the twist drill 10 can be configured simply and inexpensively as compared with, for example, a case where two cutting edge tips are separately brazed at symmetrical positions with respect to the axis. You. Further, since the polycrystalline diamond sintered body 12 is provided on each cutting edge tip 16 beyond the center of the tip of the drill, the wear resistance of the center of the tip is improved and the tool life is further improved.

Also, one end face 16c of the cutting edge tip 16
Is inclined so that the plate thickness becomes linearly thinner as the distance from the polycrystalline diamond sintered body 12 increases, and a positive rake angle α is provided by the inclination of the one end face 16c. The cutting edge chip 16 having an angle corresponding to the rake angle α can be easily obtained by cut electric discharge machining or grinding with a diamond grindstone.

Next, another embodiment of the present invention will be described. In the following description, the same parts as those of the above-described embodiment are denoted by the same reference numerals, and detailed description is omitted.

FIG. 6 is a view corresponding to FIG. 5,
In this case, the cutting edge tip 30 has a constant plate thickness at the lower end portion 30e where the polycrystalline diamond sintered body 12 is not provided, and only the portion of the one end surface 30c other than the lower end portion 30e is inclined to be positive. In this case, a rake angle is provided. In this case, substantially the same effects as in the above embodiment can be obtained. The mounting groove 32 of the drill body 14 also
The walls near the groove bottom are parallel, and only the upper part is expanded.

FIGS. 7 (a) to 7 (c) correspond to FIGS. 2 (a) to 2 (c), and FIG. 7 (d) is a sectional view taken along line DD in FIG. 7 (b). However, in this case, the cutting edge chip 40 has a constant plate thickness, and a concave groove 42 whose groove bottom section is smoothly curved like a chip breaker is provided continuously to the cutting edge 12a along the cutting edge 12a. In this case, a predetermined rake angle is provided on the cutting edge 12a, and a mounting groove having both wall surfaces parallel to each other may be provided on the drill body side. Concave groove 42
Can be formed by grinding using a diamond grindstone whose outer peripheral surface is curved corresponding to the concave groove 42.

FIGS. 8A and 8B show a case where the present invention is applied to a straight-edged drill 52 in which the chip discharge groove 50 is parallel to the axis. FIG. 8A is a plan view as viewed from the tip side, and FIG. FIG. 4 is a front view seen from a right angle direction, and is a drill body 5 made of cemented carbide;
4 and a pair of cutting edge tips 56 brazed to the tip of the drill body 54 with silver brazing, except that the chip discharge groove 50 is parallel to the axis.
The configuration is substantially the same as that of the twist drill 10.

Although the embodiments of the present invention have been described in detail with reference to the drawings, these embodiments are merely one embodiment, and the present invention is based on the knowledge of those skilled in the art. Can be implemented.

[Brief description of the drawings]

FIG. 1 is a view showing a tip portion of a twist drill to which the present invention is applied, (a) is a plan view seen from the tip side, (b) is a front view seen from a direction perpendicular to the axis, (c) () Is a right side view of (b).

FIG. 2 is a view showing a cutting edge tip used in the twist drill of FIG. 1, wherein (b) is a front view, (a) is a left side view of (b), and (c) is a right side of (b). FIG.

FIG. 3 is a view for explaining a tip material of the cutting edge tip of FIG. 2;

FIGS. 4A and 4B are diagrams showing a drill body of the twist drill of FIG. 1, wherein FIG. 4A is a diagram showing the mounting groove from a direction perpendicular to the paper surface, and FIG. 4B is a right side view of FIG.

5A and 5B are diagrams showing a state in which the cutting edge tip is brazed to the drill body of FIG. 4; FIG. 5A is a diagram showing the mounting groove of the drill body from a direction perpendicular to the paper surface; FIG. It is a right view of (a).

FIG. 6 is a view showing another embodiment of the present invention, and is a view corresponding to FIG. 5;

FIG. 7 is a view showing a cutting edge tip according to still another embodiment of the present invention, wherein (b) is a front view, (a) is a left side view of (b), and (c) is
(b) is a right side view, and (d) is a DD sectional view in (b).

8A and 8B are views showing a tip portion when the present invention is applied to a straight-edged drill, wherein FIG. 8A is a plan view seen from the tip side, and FIG. 8B is a front view seen from a direction perpendicular to the axis. It is.

[Explanation of symbols]

10: Twist drill (ultra-high pressure sintered body brazing drill)
12: Polycrystalline diamond sintered body (ultra-high pressure sintered body)
12a: Cutting edge 14, 54: Drill body 16, 30, 40, 56: Cutting edge tip 16c, 3
0c: One end surface 20, 32: Mounting groove 24: Pedestal
26: Tip material 52: Straight blade drill (ultra high pressure sintered body brazing drill) d: Thickness of ultra high pressure sintered body t:
Cutting edge chip thickness (slice width) α: Rake angle of cutting edge

Claims (3)

[Claims] 1. An ultra-high pressure sintered body in which a cutting edge tip having an ultra-high pressure sintered body is integrally brazed to a tip of a drill body, and a ridge at a corner of the ultra-high pressure sintered body functions as a cutting edge. A brazing drill, wherein the cutting edge chip is a thin plate shape obtained by slicing a chip material obtained by integrally sintering the ultra-high pressure sintered body at a predetermined thickness on a pedestal of a cemented carbide at an ultra-high pressure in a thickness direction. The tip material is brazed in such a manner that the surface side of the ultrahigh-pressure sintered body in the chip material becomes a flank surface, and one end surface side of the slice becomes a rake face, and the cutting edge has a positive edge. An ultra-high pressure sintered body brazing drill characterized by having a rake angle. 2. The cutting edge tip has a substantially isosceles chevron corresponding to the shape of a drill tip.
The ultrahigh-pressure sintered body is provided along one of the sides, and a mounting groove having a width dimension approximately twice as large as the slice width of the cutting edge tip is provided at the tip of the drill body. The two cutting edge tips are provided so as to intersect with each other, and are inserted into the mounting grooves in the opposite direction so that the ultrahigh-pressure sintered bodies are symmetrically positioned with respect to the axis, and are brazed. 2. The ultra-high pressure sintered compact brazing drill according to claim 1, wherein: 3. The one-end face of the cutting edge tip, which is a rake face, is inclined so that the plate thickness decreases linearly as the tip is separated from the ultrahigh-pressure sintered body. 3. The ultrahigh-pressure sintered compact brazing drill according to claim 1, wherein the positive rake angle is provided.