JP2003275915A - Method of manufacturing cemented carbide drill with oil hole and cemented carbide drill with oil hole - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill manufacturing method for operating no high loading effect to an extrusion device even in manufacturing a cemented carbide drill with an oil hole having an extremely small diameter cutting edge portion using extrusion press molding. <P>SOLUTION: The cemented carbide drill with the oil hole comprises the cutting edge portion 5 formed on the front end side of a cemented carbide drill body 1 being approximately columnar with an axial line O as a center to form a cutting edge 7 having an outer diameter of less than 1 mm at the front end, and a shank portion 6 formed on the rear end side thereof, wherein the oil hole is formed in the drill body 1 ranging from the shank portion 6 to the front end of the cutting edge portion 5. The manufacturing method comprises forming a through-hole 2 in the drill body 1 along the axial line O, sealing an opening portion on the front end side of the through-hole 2 with a sealing material 3, and forming a branch hole 4 communicating with the through-hole 2 via the front end of the drill body 1 in the oblique direction of the axial line O to form the oil hole opening to the front end of the drill body 1 with the through-hole 2 and the branch hole 4. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a cemented carbide alloy oil hole drill having oil holes formed in a drill body, and a cemented carbide alloy oil hole drill manufactured by such a manufacturing method. In particular, the present invention relates to a method for manufacturing a cemented carbide alloy oil hole drill and a cemented carbide oil hole drill which are suitable when the outer diameter of the cutting edge is an extremely small diameter of less than 1 mm.

[0002]

2. Description of the Related Art As a method of manufacturing a drill with an oil hole of this type, for example, Japanese Patent Laid-Open No. 11-293303 discloses a
By extrusion-pressing a cemented carbide press raw material through a mold equipped with pins while twisting spirally around the axis, a press-formed body having twist holes that serve as oil holes is formed. After sintering, form a chip discharge groove that twists spirally so as to avoid the oil hole and form a cutting edge at the tip thereof, and the tip side is the cutting edge portion and the rear end side is It has been proposed to form a drill body with a shank. Therefore, according to such a manufacturing method, even if the outer diameter of the cutting edge is a small diameter of about several mm, it is possible to form a spiral oil hole in the drill body made of cemented carbide. By supplying the cutting oil agent through the oil hole during drilling, it is possible to smoothly discharge chips and efficiently cool and lubricate the cutting portion located at the bottom of the drilled hole.

[0003]

By the way, in a very small diameter drill having an outer diameter of less than 1 mm, the cutting edge portion on the tip side has an extremely small diameter of less than 1 mm according to the outer diameter of the cutting edge. On the other hand, the shank part on the rear end side usually requires a diameter of 2 mm or more for gripping on the rotating shaft of the machine tool, so the drill body is on the rear end side with respect to the cutting edge part on the tip side The shank part of the above will have a multi-stage cylindrical shape in which the diameter is expanded by one step, and when such a drill is to be manufactured by the manufacturing method as described above, the outer diameter of the press-formed product is set to the outside of the shank part. While forming according to the diameter, the diameter of the spiral of the twist hole that becomes the oil hole is set to be small according to the diameter of the cutting edge part, and the tip side that becomes the cutting edge part after sintering this press molded body Minimal diameter of less than 1 mm depending on the outer diameter of the cutting edge So that the Yuku is scraped. However, in this way, while twisting the large-diameter press-formed body that matches the outer diameter of the shank portion in accordance with the twist of the twist hole that is formed in the cutting edge portion of the extremely small diameter and draws a spiral with the extremely small diameter, When extrusion press molding is attempted, the twisting angle when pushing out the press molded body while rotating it about the axis becomes large, resulting in a high press pressure, and in some cases, a load exceeding the withstand pressure limit of the extrusion device acts. May damage the device.

The present invention has been made under such a background, and in particular, as described above, an oil hole is formed inside by having a very small diameter cutting edge portion and a larger diameter shank portion. When manufacturing a drill with a cemented carbide oil hole using extrusion press molding, it provides a manufacturing method that does not apply a high load to the extrusion equipment, and by such a manufacturing method, especially a cutting edge part of extremely small diameter An object of the present invention is to provide a cemented carbide drill with an oil hole, which has a large-diameter shank portion and an oil hole and can reliably discharge chips and cool and lubricate a cutting portion.

[0005]

In order to solve the above-mentioned problems and to achieve such an object, a method of manufacturing a drill with oil holes made of cemented carbide according to the present invention is The leading end side of the substantially cylindrical drill body is formed as a cutting blade portion, and a cutting blade having an outer diameter of less than 1 mm is formed at the leading end thereof, and the rear end side of the drill body is formed as a shank portion. In the method of manufacturing a cemented carbide drill with an oil hole in which an oil hole is formed from the shank portion to the tip of the cutting edge portion, a through hole is formed in the drill body along the axis, and the through hole is formed. The tip side opening of the hole is sealed with a sealing material, and a branch hole communicating with the through hole is formed from the tip of the drill main body in a direction oblique to the axis line. The tip of the drill body depending on the hole Opening to the parts and forming the oil holes. Further, the cemented carbide drill with an oil hole of the present invention is such that the tip side of the substantially cylindrical drill body made of cemented carbide centering on the axis is the cutting edge portion and the tip has a cutting diameter of less than 1 mm. A drill with a cemented carbide oil hole in which a blade is formed and a rear end side of the drill body is a shank portion, and an oil hole is formed in the drill body from the shank portion to the tip of the cutting edge portion. In the above, the through hole is formed in the drill body along the axis, the tip side opening portion of the through hole is sealed by a sealing material, and the drill body tip portion communicates with the through hole. Is formed in a direction obliquely intersecting the axis, and the through hole and the branch hole form the oil hole that opens to the tip of the drill body.

Therefore, according to the manufacturing method of the above construction, the oil hole formed in the drill body is not formed in a spiral shape twisted around the axis line as in the conventional case, but is formed in a straight line shape along the axis line. Even when forming the body by extrusion press molding of cemented carbide press raw material, there is no need to extrude this molded body while twisting it in a spiral shape, and therefore the outer diameter of the cutting edge is Even if the outer diameter of the shank portion is large with a very small diameter of less than 1 mm, it is possible to prevent an excessive load from being exerted by a high press pressure that exceeds the pressure limit of the extruder. However, if the outer diameter of this cutting edge is too small, it may not be possible to form a through hole that will be an oil hole inside by extrusion press molding, so the outer diameter of this cutting edge is 0.3 mm or more. Is desirable. Further, in the cemented carbide drill with an oil hole having the above-mentioned configuration, by making the oil hole linear in this way,
Since the length thereof is shorter than that of the twisted hole, there is an advantage that it is possible to promote more efficient supply of the cutting fluid.

Here, in the above manufacturing method, when the tip side opening of the through hole is sealed with a sealing material, the drill main body in which the through hole is formed is formed by extrusion press molding a cemented carbide press raw material. After pre-sintering the body, and then filling the opening on the tip side of this through hole with a sealing material made of cemented carbide material and forming a branch hole from the tip of the drill body, the drill body together with the sealing material By sintering and sealing the tip side opening of the through hole, the manufacturing process can be simplified and the tip of the drill body is integrally sintered with cemented carbide to form a It is possible to secure high strength for the blade and the drill body. Further, in the cemented carbide drill with oil holes in which the sealing material is formed of cemented carbide and is integrally sintered with the drill body in this way, it is high even if a cutting edge or a chisel is formed on the sealing material. Can give strength.

[0008]

1 to 3 show one embodiment of a method for manufacturing a cemented carbide drill having an oil hole according to the present invention, of which FIG. 3 shows one embodiment of this manufacturing method. It also shows one embodiment of the cemented carbide drill with oil holes manufactured by the present invention. In the manufacturing method of the present embodiment, first, a cemented carbide press raw material obtained by kneading a cemented carbide raw material and a petroleum-based wax is extruded in the direction of the axis O through a mold having a pin in the center, By extrusion press-molding a molded article having an outer cylindrical shape, cutting this molded article into a predetermined length, and then temporarily sintering it,
A cylindrical drill body 1 is also formed. However, in the present embodiment, at the time of this extrusion press molding, the molded body is not pushed out while being twisted, and only one pin is provided in the center portion of the mold, whereby the drill body 1 is provided. The hole formed in the inner peripheral portion of is formed as a through hole 2 having a circular cross section that extends straight along the axis O without being twisted about the axis O. Furthermore, the outer diameter of the cylindrical drill body 1 that has been temporarily sintered in this way is set to 2 mm or more in accordance with the outer diameter of the shank portion of this drill with an oil hole that is gripped by the rotating shaft of the machine tool. The inner diameter of the through hole 2 is smaller than the outer diameter of the cutting blade provided in the oil hole drill.

Next, as shown in FIG. 2, a sealing material 3 is filled in the opening portion on the tip side (right side in the figure) of the through hole 2 of the drill body 1, and the tip side of the through hole 2 is filled. The opening is sealed to a predetermined depth, and a branch hole 4 is formed in a direction oblique to the axis O from the outer peripheral side of the front end surface of the drill body 1 toward the inner peripheral side of the rear end to form a sealing material. The portion sealed by 3 is made to communicate with the through hole 2 immediately on the rear end side. In the present embodiment, as shown in FIG. 2, the pair of branch holes 4 and 4 are formed symmetrically with respect to the axis O and extend on a plane including the axis O, and each branch hole 4 has a cross section. It has a circular shape and its cross-sectional area is smaller than that of the through hole 2.

The tip end side opening of the through hole 2 is sealed by the sealing material 3 and the drill body 1 having the branch holes 4 and 4 is fired in this way, whereby the sealing material 3 is formed.
The cemented carbide material and the drill body 1 are sintered while being diffusion-bonded to seal the tip side opening of the through hole 2 in a liquid-tight manner, and the provisionally sintered drill body 1 is completely Then, the cutting edge portion 5 is formed at the tip of the drill body 1 to form the drill with oil holes of the present embodiment as shown in FIG. That is, the tip side of the rear end of the drill body 1 left as the shank portion 6 is ground to a diameter substantially equal to the outer diameter of the cutting edge given to the oil hole drill, and then the diameter is reduced. A pair of chip discharge grooves (not shown) twisted around the axis O are formed symmetrically around the axis O on the outer circumference of the reduced diameter tip portion, and the tip end surface of the drill body 1 has an outer peripheral side and A tip flank that inclines toward the rear end as it goes to the rear side in the direction of rotation during drilling of the drill is formed, and the ridgeline of the intersection between the wall surface and the tip flank of the chip discharge groove that faces the above rotation direction. The cutting edges 7, 7 are formed on the part. Therefore, these cutting blades 7, 7 are also symmetrically formed on opposite sides of the axis O, and are given a predetermined tip angle toward the outer peripheral side toward the rear end side.

Here, the chip discharge groove is formed so that the opening on the tip flank thereof avoids the openings of the branch holes 4 and 4 on the tip flank, and therefore these chips are discharged. For the cutting edges 7 and 7 formed on the ridge line intersecting the wall surface facing the rotation direction of the groove and the tip flank,
The openings of the branch holes 4 and 4 are adjacent to the circumferential direction of the drill body 1 and are opened in the tip flank. Further, the depth of the chip discharge groove is set so as not to reach the through hole 2. Further, in the present embodiment, the outer diameter of the cutting blades 7, 7 thus formed is set to be a minimum diameter of less than 1 mm, and thus the outer diameter of the cutting blade portion 5 is also set to a minimum diameter of less than 1 mm. Becomes A back taper or an undercut may be provided on the outer periphery of the cutting edge portion 5.

Therefore, in the cemented carbide drill with an oil hole of the present embodiment manufactured as described above, the through hole 2 formed in the drill body 1 as shown in FIG. 3 and the through hole 2 With the branch holes 4 and 4 communicating with the opening to the tip flank, an oil hole is formed in the drill body 1 from the rear end of the shank portion 6 to the tip of the cutting blade portion 5. Are opened so as to be adjacent to the rear side in the rotation direction of the cutting blades 7, 7 at the tip flank. At the time of drilling, the shank portion 6 is gripped by the rotary shaft of the machine tool, and the cutting oil is supplied from the rear end of the shank portion 6, that is, the rear end of the drill body 1 to the oil hole. , A cutting oil is discharged from the opening in the tip flank through the oil hole to cool and lubricate the cutting portion of the hole bottom of the processed hole by the cutting blades 7, 7.
Further, the chips generated by the cutting blades 7, 7 are pushed out and discharged from the processed hole through the chip discharge groove. Therefore, according to the cemented carbide drill with an oil hole having the above-described configuration, the cutting site becomes hot due to the processing heat, the wear of the cutting blades 7, 7 is promoted, and the drill body 1 is broken due to clogging of chips. It is possible to prevent such a situation, and even if the outer diameter of the cutting blades 7, 7 is extremely small, less than 1 mm, it is possible to secure the life of the drill and perform stable drilling work. Becomes Moreover, this oil hole is the drill body 1
Since it is composed of a linear through hole 2 extending from the rear end to the vicinity of the tip flank and a straight through hole 2 and branch holes 4 and 4 that branch obliquely from the through hole 2 and open to the tip flank. The total length of the oil hole is shorter than that of the conventional drill in which the oil hole is formed by the twisted hole, so that the cutting oil can be efficiently supplied.

In the method of manufacturing a cemented carbide drill with an oil hole, in forming the drill body 1 by sintering a compact formed by extrusion press molding a cemented carbide press raw material as described above. Since the through hole 2 is only formed in a straight line along the axis O of the drill body 1, there is no need to push out the molded body while twisting it during this extrusion press, and therefore, unlike the conventional case. It is possible to reduce the load acting on the extrusion device without the need for an excessive press pressure for increasing the twisting angle of the extrusion device, and to prevent the extrusion device from being damaged. In particular, as described above, in a cemented carbide drill with an oil hole having an extremely small cutting edge outer diameter of less than 1 mm, an oil hole must be formed inside the cutting edge portion where the outer diameter becomes extremely small. On the other hand, the shank part must have an outer diameter of 2 mm or more that can be gripped by the rotating shaft of the machine tool. Therefore, if the oil hole is formed in a spiral shape, the molded body of the drill body is extruded and pressed. The twisting angle at the time of forming becomes extremely large, while the manufacturing method and the drill with a cemented carbide oil hole having the above-described configuration increase the press pressure regardless of the outer diameter difference between the cutting edge portion 5 and the shank portion 6. Since it can be suppressed, it is particularly effective when applied to such an ultra-small diameter cemented carbide drill with an oil hole and its manufacture.

Further, in the manufacturing method of this embodiment, in order to seal the front end side opening of the through hole 2 of the drill body 1 with the sealing material 3, the molded body obtained by the extrusion press is provisionally sintered to form a cylindrical shape. Of the drill body 1 and the through hole 2 in the inner peripheral portion thereof.
The opening 3 is filled with the sealing material 3 and the branch hole 4,
4 is formed, and the through hole 2 is sealed by sintering the sealing material 3 together with the drill body 1 so as to be diffusion bonded. However, in this respect, for example, a disc-shaped cap member made of sintered cemented carbide is also brazed to the tip surface of the drill body made of cemented carbide that is sintered into a cylindrical shape as in the above embodiment. To seal the through hole,
It is also possible to form a branch hole, a tip flank, or a chip discharge groove on the tip of the drill body including the cap member to provide a cutting edge portion, but with such a manufacturing method. , A process of brazing the cap member to the tip of the drill body is required, and branch holes must be formed in the sintered high-hardness cap member and the drill body, which may complicate the manufacturing process. In some cases, the brazing material layer at the time of brazing may be exposed on the cutting edge or the tip flank, and the strength of the cutting edge or the strength of the drill body may be impaired. On the other hand, in the manufacturing method of the present embodiment, since the drill body 1 and the sealing material 3 made of cemented carbide are sintered and joined together when the drill body 1 is sintered, the manufacturing is performed. The process is simple, and the drill thus obtained can have high strength even if the cutting blade 4 and the chisel of the center of rotation of the tip of the drill body 1 are formed on the sealing material 3.

[0015]

As described above, according to the method for manufacturing a cemented carbide alloy drill with an oil hole of the present invention, when forming a drill body having an oil hole, a cemented carbide press raw material is extruded. Even when this drill body is formed by press forming, the press pressure can be reduced, which prevents an excessive load that exceeds the pressure limit of the extrusion device from acting and the cutting edge. Even if the outer diameter of the drill is extremely small, it is possible to promote reliable and smooth manufacturing of the drill. In addition, in the cemented carbide drill with an oil hole of the present invention manufactured in this manner, even when the outer diameter of the cutting edge is small, a sufficient outer diameter is secured in the shank portion to grip the machine tool. It is possible to reliably supply the cutting oil through the oil hole to promote smooth chip discharge and cooling and lubrication of the cutting site, while shortening the total length of the oil hole for more efficient operation. It is also possible to supply various cutting fluids.

[Brief description of drawings]

FIG. 1 is a side sectional view of a drill body 1 after pre-sintering according to an embodiment of a manufacturing method of the present invention.

FIG. 2 is a perspective view of the drill body 1 shown in FIG.
FIG. 4 is a side sectional view showing a state in which the is formed.

FIG. 3 is a side sectional view showing an embodiment of a cemented carbide drill with oil holes according to the present invention, in which a cutting edge portion 6 is formed after sintering the drill body 1 shown in FIG.

[Explanation of symbols]

1 drill body 2 Through hole (oil hole) 3 Sealant 4 branch holes (oil holes) 5 cutting edge 6 Shank part 7 cutting edge O Drill body 1 axis

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Higashi             1528, Nakashinden, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture             Address Mitsubishi Materials Corporation Gifu Factory             Within F-term (reference) 3C037 DD06 FF04

Claims (4)

[Claims] 1. A cutting body having a substantially cylindrical drill body made of a cemented carbide centering on an axis is formed as a cutting edge portion, and a cutting edge having an outer diameter of less than 1 mm is formed at the distal end of the drill body. The rear end side of the main body is a shank portion, and in the drill main body, in the method for manufacturing a cemented carbide oil-drilled drill in which an oil hole is formed from the shank portion to the tip of the cutting edge portion, Forms a through hole along the axis, seals the tip side opening of the through hole with a sealing material, and forms a branch hole communicating from the drill body tip with the axis to the axis. A method for manufacturing a drill with an oil hole made of cemented carbide, characterized in that the oil hole that opens at the tip of the drill body is formed by these through holes and branch holes by forming them in the intersecting direction. 2. A drill body having the through hole,
A cemented carbide press raw material is extruded and press-molded to form a compact, which is then filled with the encapsulant made of a cemented carbide material in the opening on the tip side of the through hole and the tip of the drill body. 2. The cemented carbide oil-making hole according to claim 1, wherein after forming the branch hole, the drill body is sintered together with the sealing material to seal the tip side opening of the through hole. Of manufacturing a drill with an arrow. 3. A cutting edge part is formed on the tip side of a substantially cylindrical drill body made of cemented carbide centering on the axis, and a cutting edge having an outer diameter of less than 1 mm is formed at the tip, and the drill described above. A rear end side of the main body is a shank portion, and in the drill main body, in a drill with a cemented carbide oil hole in which an oil hole is formed from the shank portion to the tip of the cutting edge portion, the axis of the drill body is the axis line. A through hole is formed along with the through hole, and a tip end side opening portion of the through hole is sealed by a sealing material, and a branch hole communicating with the through hole from the drill body front end portion obliquely intersects with the axis line. Is formed in the direction
A drill with an oil hole made of cemented carbide, characterized in that the through hole and the branch hole form the oil hole opening at the tip of the drill body. 4. The cemented carbide drill with oil holes according to claim 3, wherein the sealing material is formed of cemented carbide and is sintered integrally with the drill body.