JP2003266238A - Boring tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boring tool to provide high precision even in high speed cutting. <P>SOLUTION: In the boring tool 21 provided with a chip discharge groove 25 notched in the outer periphery of a rod-form tool body 23, rotating around an axis O, and in a direction extending from a tip surface 37 along the axis O; and a cutting edge 29 attached to the inner wall surface of the chip discharge groove 25 turned toward the rotation direction of the tip of the tool body, a counter boring part 39 to coincide a deviated center of gravity with the axis O is formed at the tip surface of the tool body 23 in a state to be deviated from the axis O. Further, the boring tool 21 may be formed that a fine hole with a bottom for adjustment to coincide a deviated center of gravity with the axis O is bored in a direction extending from the tip surface 37 of the tool body 23 along the axis O. <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 hole drilling tool for finishing the inner surface of a hole that has already been drilled, and more particularly to an improved technique capable of obtaining high drilling accuracy even in high speed cutting.

[0002]

2. Description of the Related Art For hole drilling, there is a drilling method for finishing the inner surface of a hole that has already been drilled more precisely. Examples of tools used for this are reamers and gun reamers used for finishing deep holes. There is a hole processing tool. As this hole drilling tool, a single-blade or multi-blade tool is selected according to the application and required machining accuracy. Generally, the single-blade reamer is suitable for drilling holes with high accuracy such as coaxiality, roundness, and straightness, and the multi-blade reamer has an advantage that the machining efficiency can be increased by the number of blades. The reason why the single-blade reamer is excellent in hole accuracy is that there is only one cutting blade, so there is no effect of cutting blade variations that occur on multiple blades, and the cutting force is always applied in a fixed direction to stabilize the cutting state. There are things to do.

Conventionally, this type of single-edged hole drilling tool 1 is
As shown in FIGS. 3 and 4, on the outer circumference of the rod-shaped tool body 3,
Chip discharge groove 5 notched in the direction along the axis O from the tip surface
Is provided. A cutting edge (chip) 9 made of a hard material such as cemented carbide is attached to the inner wall surface 7 of the chip discharge groove 5 facing the tool rotation direction at the tip of the tool body by brazing or the like via a sheet member 11. . On the outer circumference of the tool body 3,
A margin portion 13 is formed along the cutting edge 9 behind the chip discharge groove 5 in the tool rotation direction, and further behind this margin portion 13 in the tool rotation direction, the outer circumference of the cylinder around the axis O of the tool body 3 is the center. A planar guide pad 15 is provided. In the hole drilling tool 1 having such a structure, the tool body 3 advances while the guide pad 15 slides on the inner peripheral surface of the hole expanded by the cutting blade 9, and the axis O of the tool body 3 is aligned with the center axis of the hole. The cutting edge 9 is guided so that the two coincide with each other, the swing of the cutting edge 9 is suppressed, the straightness of the tool main body 3 is ensured, and highly accurate finishing processing is performed.

[0004]

However, in the above-described single-edged hole drilling tool, a chip discharge groove is provided on the outer periphery of the tool main body 3, and a cutting blade is attached to the inner wall surface of the chip discharge groove. Since the cutting is stabilized by applying the cutting force to the pad, the structure has a cross-sectional shape in which the center of gravity is deviated to the guide pad side, and there is a problem of imbalance during rotation. And this is
This is especially noticeable during high-speed cutting, which improves cutting efficiency.
When cutting is performed with the rotational balance unbalanced, the sliding contact torque increases, and there is a problem that the hole accuracy is reduced, and galling and seizure occur. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hole drilling tool that can obtain high machining accuracy even in high-speed cutting.

[0005]

According to a first aspect of the present invention, there is provided a hole drilling tool according to a first aspect of the present invention. In a hole drilling tool provided with a chip discharge groove cut out in No. 2 and a cutting blade attached to the inner wall surface of the chip discharge groove facing the tool rotation direction at the tip of the tool body, a counterbore for aligning the eccentric center of gravity with the axis line. The portion is formed on the tip end surface of the tool body so as to be eccentric to the axis.

In this hole drilling tool, the eccentric center of gravity due to the provision of the chip discharge groove and the cutting edge coincides with the axis of the tool body, that is, the center of rotation due to the formation of the spot facing portion, and the rotation balance becomes good. . As a result, an increase in the sliding contact torque that occurs when cutting is performed with poor rotational balance is suppressed, a decrease in hole accuracy, galling, and seizure are prevented, and high processing accuracy can be obtained even in high-speed cutting.

A hole drilling tool according to a second aspect is the hole drilling tool according to the first aspect, in which a bottomed fine hole for adjustment that causes an eccentric center of gravity to coincide with the axis is formed in a direction along the axis from the tip end surface of the tool body. It is characterized by being drilled in.

In this hole drilling tool, the position of the center of gravity can be further finely adjusted by forming the adjusting bottomed pores after the formation of the counterbore, and the center of gravity caused by the machining accuracy of the counterbore. The minute deviation between the axis and the axis can be easily removed, and the center of gravity can be more accurately aligned with the axis.

A hole drilling tool according to a third aspect of the present invention is the hole drilling tool according to the first or second aspect, in which a coolant supply passage having a diameter smaller than that of the counterbore is bored in the tool body in a direction along an axis. It is characterized in that the tip of the coolant supply passage is opened at the bottom of the spot facing portion.

In this hole drilling tool, the refrigerant, which has been conventionally directly supplied from the small diameter refrigerant supply passage coaxial with the axis at the tip end surface of the tool body, is once supplied to the eccentric large diameter spot facing portion. Then, the centrifugal force due to the rotation of the tool body effectively acts, and the refrigerant is uniformly supplied in the circumferential direction. Further, the spot facing portion also functions as a refrigerant reservoir, which also promotes the uniform supply of the refrigerant in the radial direction.

A hole drilling tool according to a fourth aspect is the hole drilling tool according to the third aspect, wherein the inner peripheral surface of the counterbore is formed by a tapered surface whose diameter increases toward the tip of the tool body. Is characterized by.

In this hole drilling tool, the coolant supplied into the counterbore moves along the tapered surface where the diameter gradually increases,
It is smoothly supplied to the tip side of the tool body. Further, since the tapered surface expands in diameter toward the tip, a force acting in the tip direction acts on the chips trying to enter the inside of the spot facing portion,
It is difficult for the chips at the tip of the tool body to enter the counterbore.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a hole drilling tool according to the present invention will be described in detail below with reference to the drawings. 1 is a side view of a hole drilling tool according to the present invention, and FIG. 2 is a front view of the hole drilling tool shown in FIG.

As shown in FIGS. 1 and 2, the hole drilling tool 21 according to the present embodiment has a rod-shaped tool body 23 having an outer periphery,
Chip discharge groove 2 cut away from the tip surface in the direction along the axis O
5 is provided. At the tip of the tool main body 23, a cutting edge (chip) 29 made of a hard material such as cemented carbide is attached to the inner wall surface 27 of the chip discharge groove 25 facing the tool rotation direction by brazing or the like via a sheet member 31. There is.

On the outer periphery of the tool body 23, along the cutting edge 29, there is a margin portion 33 behind the chip discharge groove 25 in the tool rotation direction.
A guide pad 35 having a cylindrical outer peripheral surface centering on the axis O of the tool body 23 is provided further behind the margin portion 33 in the tool rotation direction. Hole processing tool 2
1 is a cutting blade 2 such that the tool body 23 advances while the guide pad 35 slides on the inner peripheral surface of the hole expanded by the cutting blade 29, and the axis O of the tool body 23 coincides with the central axis of the hole.
9 will be guided.

A counterbore 39 is formed on the tip surface 37 of the tool body 23 so that the eccentric center of gravity coincides with the axis O. The spot facing portion 39 is arranged eccentrically with respect to the axis O in the xy directions of FIG. 2 by a distance of dx, dy. That is, in the cross-sectional shape shown in FIG. 2, the area on the opposite side of the chip discharge groove 25 across the axis O is largely removed, so that the center of gravity deviated from the axis O is corrected so as to coincide with the axis O. This counterbore 39 is a parameter for moving the center of gravity toward the axis O by setting the depth L arbitrarily.

The counterbore 39 may be machined before the cutting blade 29 is attached. In this case, the eccentricity of the center of gravity caused by attaching the cutting edge 29 can be eliminated by forming the adjusting bottomed fine hole 41 in the tip surface 37 of the tool body 23 in the direction along the axis O. . This bottomed fine hole 41 for adjustment is used for the tool body 23 after the cutting blade 29 is attached.
It may be provided in the. That is, by forming the adjustment bottomed pores 41 after the formation of the spot facing portion 39, the position of the center of gravity can be further finely adjusted, and the center of gravity generated by the processing accuracy of the spot facing portion 39 and the axis O. It is possible to easily remove the minute deviation of the above and match the center of gravity with the axis O with higher accuracy.

The tool main body 23 has a coolant supply passage 43 for supplying a coolant such as oil to a cutting location. The refrigerant supply passage 43 has an inner diameter smaller than that of the spot facing portion 39, and the axis O
(In the present embodiment, coaxial with the axis O). The tip of the coolant supply passage 43 opens at the bottom portion 45 of the spot facing portion 39. Therefore, the coolant supplied to the coolant supply passage 43 flows into the spot facing portion 39 and then is supplied from the tip of the tool body 23 to the cutting location. The coolant acts to cool the cutting site and improve the chip discharge property.

The coolant supply passage 43 has a bottom portion 4 of the spot facing portion 39.
By opening at 5, the tip surface 37 of the tool body 23 is conventionally formed.
Then, the refrigerant which has been directly supplied from the small diameter refrigerant supply passage coaxial with the axis O is once supplied to the eccentric large diameter spot facing portion 39. As a result, the centrifugal force due to the rotation of the tool body 23 effectively acts, and the refrigerant is uniformly supplied in the circumferential direction. Further, the spot facing portion 39 also functions as a refrigerant reservoir, which also promotes the uniform supply of the refrigerant in the circumferential direction.

When the coolant supply passage 43 is opened to the spot facing portion 39, the inner peripheral surface of the spot facing portion 39 is
It is preferable to form the taper surface 47 whose diameter increases toward the tip of the tool body 23. If the inner peripheral surface of the spot facing portion 39 is formed by the tapered surface 47, the refrigerant supplied into the spot facing portion moves along the gradually increasing tapered surface 47 and is smoothly supplied to the tip end side of the tool body. The Rukoto. Further, since the taper surface 47 expands in diameter toward the tip, a force acting in the tip direction acts on the chips that try to enter the counterbore 39, so that the chips at the tip of the tool body are inside the counterbore 39. Becomes difficult to enter. As a result, it is possible to prevent chips from entering the counterbore 39 and causing the center of gravity to shift.

According to the hole drilling tool 21 described above, the center of gravity that is eccentric due to the provision of the chip discharge groove 25 and the cutting edge 29 becomes the axis O of the tool body 23, that is, the center of rotation by the formation of the spot facing portion 39. They match and the rotation balance is good. As a result, an increase in the sliding contact torque that occurs when cutting is performed with poor rotational balance is suppressed, a decrease in hole accuracy, galling, and seizure are prevented, and high processing accuracy can be obtained even in high-speed cutting.

In the above embodiment, the spot facing portion 3
The case where 9 is a perfect circle has been described as an example, but in the hole drilling tool according to the present invention, the counterbore has another shape, for example, the inner peripheral surface of the counterbore consisting of two perfect circles is continuous. It may be integrally formed in a cocoon shape by stacking the two. The counterbore may have different radii and may be formed coaxially in a stepped shape. Furthermore, the counterbore may be formed by inclining at a predetermined angle with respect to the axis O of the tool body 23.

[0023]

As described in detail above, according to the hole drilling tool of the first aspect of the present invention, the counterbore portion for aligning the eccentric center of gravity with the axis line is provided on the tip end surface of the tool body. Since it is formed with eccentricity, the eccentric center of gravity by providing the chip discharge groove and cutting edge coincides with the axis of the tool body, that is, the center of rotation due to the formation of the spot facing portion, and improves the rotation balance. be able to. As a result, high machining accuracy can be obtained even in high-speed cutting.

According to the hole drilling tool of the second aspect, since the adjusting bottomed fine hole for aligning the eccentric center of gravity with the axis is bored in the direction along the axis from the front end surface of the tool body, After the formation, it is possible to finely adjust the position of the center of gravity by forming the bottomed fine pores for adjustment, and it is possible to easily remove the minute deviation between the center of gravity and the axis caused by the processing accuracy of the spot facing. , The center of gravity can be aligned with the axis more accurately.

According to the hole drilling tool of the third aspect, the tool body is provided with a coolant supply passage having a diameter smaller than that of the spot facing portion in a direction along the axis, and the tip of the coolant supply passage is provided with the spot facing portion. Since it was opened at the bottom, conventionally, at the tip surface of the tool body,
The refrigerant that was directly supplied from the small-diameter refrigerant supply passage that is coaxial with the axis is once supplied to the eccentric large-diameter spot facing portion, and the centrifugal force due to the rotation of the tool body is effectively applied, The refrigerant can be uniformly supplied in the circumferential direction.
In addition, the spot facing portion also functions as a refrigerant reservoir, which also promotes the uniform supply of the refrigerant in the radial direction.

According to the hole drilling tool of the fourth aspect, since the inner peripheral surface of the counterbore portion is formed by the tapered surface whose diameter increases toward the tip of the tool body, the coolant supplied into the counterbore portion can be prevented. The supply to the tip side of the tool body can be made smooth. Further, it is possible to make it difficult for the chips at the tip of the tool body to enter the counterbore.

[Brief description of drawings]

FIG. 1 is a side view of a hole drilling tool according to the present invention.

FIG. 2 is a front view of the hole drilling tool shown in FIG.

FIG. 3 is a side view of a conventional drilling tool.

FIG. 4 is a front view of the hole drilling tool shown in FIG. 3.

[Explanation of symbols]

21 ... Hole processing tool 23 ... Tool body 25 ... Chip discharge groove 27 ... Inner wall 29 ... Cutting edge 37 ... Tip surface 39 ... counterbore 41 ... Bottomed pores for adjustment 43 ... Refrigerant supply passage 45 ... bottom 47 ... Tapered surface O ... axis

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuzo Koedashi             1528, Nakashinden, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture             Address Mitsubishi Materials Corporation Gifu Factory             Within F-term (reference) 3C050 EB01 EB09

Claims (4)

[Claims] 1. A chip discharge groove cut out in the direction along the axis from the tip surface on the outer periphery of a rod-shaped tool body that rotates around an axis, and an inner wall surface of the chip discharge groove that faces the tool rotation direction at the tip of the tool body. In a hole drilling tool having a cutting edge attached to a hole, a counterbore for aligning an eccentric center of gravity with the axis is formed on the tip end surface of the tool body by eccentricity with the axis. tool. 2. The hole drilling tool according to claim 1, wherein an adjusting bottomed fine hole for aligning an eccentric center of gravity with the axis is provided in a direction along the axis from the tip end surface of the tool body. A hole drilling tool. 3. The hole drilling tool according to claim 1, wherein a coolant supply passage having a diameter smaller than that of the spot facing portion is bored in the tool body in a direction along an axis, and a tip of the coolant supply passage is provided. A hole drilling tool, characterized in that it is opened at the bottom of the spot facing. 4. The hole drilling tool according to claim 3, wherein the inner peripheral surface of the counterbore part is formed by a tapered surface whose diameter increases toward the tip of the tool body.