JPH09239613A - Diamond rotary cutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end mill with an edge of diamond or a cubic crystal boron nitride. SOLUTION: At least a pair of spiral grooves 18 are provided on a rotary cutter blank 12. In the grooves 18, a polycrystal powder diamond or a powder cubic crystal boron nitride is filled and sintered. The angle of the groove is selected to form a positive or a negative rake angle when necessary, and then, a recess form flute 14 having the edge end parallel to the edge end 15 of the polycrystal diamond filled in the groove of the blank 12 is formed neighboring the respective grooves. By grinding a diamond in such a condition, the diamond loss is extremely little, and the perfect condition of a cutter is never hurt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary cutter,
In particular, it relates to a rotary cutter with a spiral flute having a cutting edge made of a hard material containing polycrystalline diamond or the like.

[0002]

2. Description of the Related Art A rotary cutter with a spiral flute such as an end mill is required for cutting under extremely severe conditions. The cutting end of the spiral flute end mill includes at least one pair of cutting edges, one on each of the facing surfaces of the end mill material (blank).

Since axial loads and torsional loads act on the cutting surfaces of the end milling material which are located at the cutting ends and are opposite to each other, material conditions are required for the structure of the end mill cutter. Naturally, the material of the cutting edge must be as hard as possible to cut the work piece, and heat resistance is also required to maintain the cutting edge of the end mill cutter at a high temperature. Further, during use of the end mill cutter, since the end mill cutter under load resists bending and maintains the outer shape, the material of the main body of the end mill material must have both rigidity and toughness. However, in general, a hard material is brittle and a high toughness material is easily worn. Therefore, if the above conditions are to be satisfied, a compromise must be made in material selection.

The present invention is also applicable to various image cutting tools such as grooving mills, drills, counterbore, counterbore, reamers, taps and the like.

It is known to combine a material having hardness and wear resistance in the cutting surface with a material having high toughness and high rigidity in the main body and the shaft. It has already been proposed to form the cutting surface and the body and shaft from different materials. As a result, various combinations are known, such as a shaft made of carbon steel or carbide with a combination of tungsten carbide or diamond chips or inserts.

[0006]

Although individually useful, these combinations have common drawbacks associated with brazing between the insert or tip and the shaft. It is possible to solder or braze the tungsten carbide directly onto the steel or carbide shaft. However, the diamond tip or insert must first be bonded to the carbide base and then the base soldered or brazed to the shaft.

The diamond particles are usually formed as a compression molded body of PCD (polycrystalline diamond) and, at the same time, bonded to a carbide base in a high pressure and high temperature press through a metal catalyst. However, at atmospheric pressure, the metals that catalyze the bonding of diamond particles to each other and to the base that occur in the press also catalyze the conversion of diamond to graphite at temperatures above 700 ° C, resulting in PCD compression molding. It causes the body to collapse.

Therefore, low-temperature soldering or brazing is used to attach the base to the shaft. This brazing is
Because it is softer than the base and shaft, the useful life of such turning tools is limited. Therefore, the brazed portion is the greatest weak point of the tool structure, and becomes a factor that restricts the use of the tool.

US Pat. No. 4,762,445 discloses a vein of sintered abrasive particles, eg polycrystalline diamond, in a drilling material composed of a material having a relatively low abrading capacity, eg carbide. Disclosed is a twist drill device with a spiral flute, in which shaped compacts are embedded in a position opposed to each other in a branched manner. At the tip of the drill and near the web, the striations of abrasive material are disturbed out of parallel and interlace with each other. The diamond streaks are facing each other by opening at 180 ° C at the tip of the spiral drilling material.

The opposed muscle vein shaped bodies intersect at the center of the spiral drill, that is, the center of the axis, so that the diamond is concentrated at the tip of the twist drill. However, the diamond streaky compact at the tip of the twist drill is relatively shallow and wears in a short time.

[0011]

The present invention overcomes the problems of the prior art by, for example, concentrating diamond in each of at least a pair of preformed grooves. The groove provided in the rotary cutting material is formed with an appropriate rake angle that minimizes the amount of base material cut from the vicinity of the diamond when forming the rotary cutter flute.

According to the above-mentioned known technique, a groove that is aligned in the radial direction is formed in the material for rotary cutting, and then the diamond cutter material is sintered in this groove. After fixing diamond in each groove by diamond sintering process, when forming a flute on the mandrel of the rotary cutter, especially when it is desired to make the diamond form a positive rake angle with respect to the workpiece Most of the diamond leading edge will be scraped off.

The present invention provides a method for forming a diamond-filled groove that matches the leading edge cutting edge angle of sintered diamond, whether the angle to adjacent workpieces is positive, negative or 90 °. .

By carefully forming the diamond-filled groove so as to have an appropriate cutting angle, it is possible to avoid cutting the sintered diamond from the groove when forming the flute on the mandrel of the rotary cutter, and to cut the diamond. It is possible to easily form the flute while maintaining the whole of the sintered diamond in the process.

In the rotary cutter of the present invention, the diamond is left as it is during the manufacturing process, so that it has a longer service life and a lower manufacturing cost than conventional ones.

The present invention provides a rotary cutter with a spiral flute in which each of the spiral grooves formed in the rotary cutter work material forms a positive or negative rake angle with respect to the workpiece. The grooves are filled with a compression compact made of polycrystalline diamond (PCD) or cubic boron nitride (CBN). The concave flutes are then formed at an angle that matches the angle of the groove. Therefore, when cutting a diamond or CBN with a positive or negative rake angle,
BN loss is extremely low.

The diamond rotary cutter is manufactured by first forming at least a pair of grooves on the side surface of the rotary cutter work material. The groove is radially engraved and is formed such that the angle of its edges approximately matches the angle of the concave flutes subsequently formed in the rotary cutter blank. A spiral groove formed in a rotary cutter material is filled with a hard material selected from either a polycrystalline diamond type or a cubic boron nitride type. The polycrystalline hard material is formed by sintering the hard material in the groove of the rotary cutter material under sufficient high pressure to sinter it. While forming a concave flute in the rotary cutter processing material almost parallel to the edge of the hard material of the spiral groove and grinding the hard material at an angle that almost matches the edge angle of the hard material, while minimizing the hard material loss Forming a cutting edge of hard material along the front edge of the sintered hard material.

[0018]

Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. Diamond end mill 1 in Figure 1
0 is made of the end mill processing material 12, and has, for example, four flutes 14 at equal intervals in the circumferential direction around the processing material. The processing material of the end mill is preferably made of a hard and highly tough material such as tungsten carbide. The spiral groove 18 is formed in the front edge 15 of the flute 14. The twist angle of the groove is the flute 14 to be formed next.
It is set according to the shape of. The streaky compression molded body 30 is formed in the spiral groove 18 with a hard material made of sintered polycrystalline diamond (PCD) or cubic boron nitride (CBN). At a position close to the drill-shaped work material flute, the pressed and sintered diamond-shaped molded body 30 of the spiral groove 18 is ground to form a cutting edge 32. This drill-shaped workpiece made of tungsten carbide is used as the joining surface 17
Along with an intermetallic bond to a drill mandrel 16 of steel or carbide. This intermetallic bond can be made by brazing, for example.

The end face 13 of the end mill shown in FIG. 2 also shows that the spiral groove 18 forms the leading edge of the flute. Striation forming 30 composed of polycrystalline diamond (PCD) or cubic boron nitride (CBN) is disclosed in US Pat.
As detailed in 991, 467 and 5, 031, 484, the spiral groove is first filled as a powdery hard material and then subjected to high pressure pressing to compact in the groove,
It is formed by sintering. When the sintering process is completed, the PCD material is ground to form the flutes 14 and the cutting edges 32.

Since the edge angle of the material forming the groove coincides with the cutting edge angle of the sintered diamond, the grinding amount may be minimized. Therefore, it is possible to minimize the diamond loss during the blade attaching process and maintain the maximum amount of diamond in the groove.

As is apparent from FIG. 3, for example, four spiral grooves 18 are formed in the end mill material 12 made of tungsten carbide. Next, after sintering the diamond in the groove, flutes are formed on the end mill body. The spiral grooves are evenly spaced in the circumferential direction along the outer peripheral wall of the processed material, and play the role of a container in which the powder PCD is packed.

The mutually angled sidewalls 20 of the spiral groove are preferably configured to transition to the rounded bottom 22 of the groove. A matching sidewall 20 is provided in each groove.
The reason for rounding the groove bottom is to fill the groove with polycrystalline powder diamond so that voids do not occur. If the side wall of the groove is formed at 90 ° with respect to the bottom, a sharp corner of 90 ° is formed, which may cause stress concentration to form a void in the diamond material.

In FIG. 4, a pair of spiral grooves 1 is formed on the work material 112.
An example of another end mill material 110 having 18 formed therein is shown.

The diamond cutter may be provided with one or more spiral grooves that are substantially parallel to the axis of the rotary cutter material. Furthermore, rotary cutter processing materials 12, 112
It is also possible within the scope of the present invention to provide vertical milling and horizontal milling effects by providing cutting edges that traverse the end faces 13 and 113, respectively.

As is apparent from FIGS. 1, 2 and 5,
The spiral grooves 18, 118 are filled with powdered diamond (or powdered boron nitride) and sintered in a press at a pressure high enough to form a polycrystalline material. In this way, a polycrystalline diamond solid state is formed in the spiral groove on the side surface of the end mill processed material. Next, grind the end mill processing material and flute 1
4 is formed. Since the spiral groove is formed by cutting in accordance with the angle of the flute formed in the work material, the cutting edge 32 is formed on the side surface of the work material with the minimum diamond loss in the next grinding step.

FIG. 6 is a sectional view showing a conventional end mill 210 having a groove 218 formed in a mandrel body 212.
Since the diamond material 230 and the groove 218 are formed in the radial direction, when the flute 214 is formed on the mandrel main body 212 and the diamond material is bladed, at least 1/3 of the diamond material 230 is shown as indicated by the shaded area 217. Is lost.

This diamond loss is particularly inconvenient when a positive cutter rake angle "A" is provided.
Not only a great amount of time is required to grind the diamond material 230, but also a heavy load is imposed on the tool grinding device. In addition, diamond loss shortens the useful life of the diamond cutter.

In the embodiment shown in FIG. 7, the grooves 318 of the PCD-packed rotary cutter mandrel 312 are angled from the radial line to align with the concave flutes 314. Furthermore, the cutting edge 332 of the diamond material 330 forms a positive rake angle with respect to an adjacent workpiece (not shown). Angle "B" is the rake angle of cutting edge 332.

When forming the flutes in the work material, the work material is scraped off parallel to the cutting surface 319 and tangential to the bottom 317 of the diamond material 330. It is clear how little diamond material is lost in the flute forming process as well as the diamond edging process.

As can be easily understood by comparing with the known technique of FIG. 6, if the groove is formed at a predetermined angle, the durability of the rotary cutter 310 can be remarkably enhanced and its life can be extended.

In the embodiment shown in FIG. 8, the rotary cutter 41 is used.
Form a V-shaped groove 418 in the processing material 412 of 0,
A roundness 421 is provided at the bottom of the "V". Similar to the bottom 331 (FIG. 7) in the above-described embodiment, by providing the bottom with the roundness 421, it is possible to reliably fill the powder diamond without generating voids as described above with reference to FIG.

Since the cutting surface 419 also forms a positive rake angle in this embodiment, the cutting edge 432 forms a positive rake angle with respect to the adjacent (not shown) workpiece, that is, the cutting line with respect to the cutter surface. Form a positive rake angle between them. Here again, the flutes are formed along the cutting surface 419 and migrate from the diamond cutting surface 419 at the level of the bottom 417. As described above, in the flute forming step and the diamond edging step, the diamonds removed as chips are The quantity is extremely small.

It is also possible within the scope of the invention to form diamond sintered grooves and flutes at negative rake angles.
It is also possible within the scope of the invention to form grooves and flutes that are not helical.

It goes without saying that various changes can be made in the structure and method of the present invention without departing from the concept of the present invention. That is, although the preferred construction and working mode of the present invention have been described based on the illustrated embodiment, other embodiments are possible within the scope of the appended claims.

[Brief description of drawings]

FIG. 1 is a perspective view of an end mill with a flute.

FIG. 2 is an end view taken along the line 2-2 of FIG.

FIG. 3 is a side view of an end mill processing material in which four spiral flutes are cut and formed.

FIG. 4 is a side view of an end mill blank having a pair of spiral flutes spaced 180 ° apart from each other.

5 is an end view taken along the line 5-5 of FIG.

FIG. 6 is a cross-sectional view of a conventional rotary flute-machined material for fluting, which is formed by aligning grooves filled with sintered diamond in a radial direction.

FIG. 7 is a cross-sectional view of a rotary cutting material with a flute in which a spiral flute intersects a radial line to form a diamond cutting edge forming a positive rake angle.

FIG. 8 is a cross-sectional view of a fluted rotary cutter stock having a "V" shaped groove that intersects a radial line to form a diamond cutting edge that makes a positive rake angle with the work piece.

[Explanation of symbols]

 10 Diamond End Mill 12 End Mill Processing Material 13 End Mill End Surface 14 Flute 15 Leading Edge 18 Spiral Groove 20 Sidewall 22 Bottom 30 Muscle Compression Molded Body 32 Cutting Edge

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Claims (9)

[Claims] 1. A hard material selected from one of a polycrystalline diamond-based material and a cubic boron nitride-based material, in which at least a pair of grooves are formed in a side wall of a rotary cutting material having first and second ends. In the rotary cutter fixed in the groove, the grooves are formed by radial engraving along an angle that is adjacent to each of the grooves and that matches a helix angle of a flute formed in the rotary cutter work material, and then A diamond rotary cutter characterized in that the flute and the cutting edge are formed along an inclined front edge formed by the hard material by grinding the hard material and the rotary cutter processing material. 2. The diamond rotary cutter according to claim 1, wherein the direction of the groove is set so as to form a positive rake angle with a tangent to the cutter surface. 3. The diamond rotary cutter according to claim 1, wherein the direction of the groove is set so as to form a negative rake angle with a tangent to the cutter surface. 4. The diamond rotary cutter according to claim 1, wherein the groove is formed in a V shape, and the direction of the leading edge of the cutting edge is set so as to form a positive rake angle with a tangent to the cutter surface. . 5. A rotary cutter working material having a cutting end as a first end and a base as a second end is formed, and the rotary cutting work material is formed from the first cutting end toward the second base end. Forming at least a pair of grooves on the side surface, the groove formed in this rotary cutter processing material, filled with a hard material selected from any one of polycrystalline diamond-based and cubic boron nitride-based, in the groove In a method of forming a rotary cutter, comprising sintering the hard material in a high-pressure press sufficient to form a polycrystalline hardener, and forming a concave flute in the rotary cutting material at substantially the edge of the groove, The groove is carved in the radial direction, and then an edge is formed at an angle substantially corresponding to the twist angle of the concave flute formed in the rotary cutting material, the rotary cutting material By grinding the hard material formed in the groove of the hard material at an angle substantially equal to the angle of the edge of the hard material, a rake angle substantially equal to the angle of the leading edge and the edge of the sintered hard material is obtained. A method of forming a diamond rotary cutter, characterized in that a cutting edge made of a hard material is formed along the cutting edge. 6. As the groove, a sloped side wall is formed into a rotary cutting material in a "V" shape so as to define a "V" -shaped groove in which the width of the groove bottom is narrower than the groove width of the surface of the rotary cutting material. The method of forming a diamond rotary cutter according to claim 5, further comprising the step of forming, wherein the inclined sidewall forms a positive rake angle with a tangent to the surface of the cutter. 7. The method of claim 5 including the step of forming a groove at a positive rake angle with respect to an adjacent work piece. 8. The method of claim 5 including the step of forming a groove at a negative rake angle with respect to an adjacent work piece. 9. A method as claimed in any one of claims 5 to 8 including the step of brazing a proximal second end of the rotary cutter to a cutter mandrel.