JP2003266240A - Boring tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boring tool capable of providing high machine 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 rotated around an axis O in a direction extending from a tip surface 37 along the axis O; and a cutting edge 29 attached on the inner wall surface of the chip discharge groove 25 turned toward the rotation direction of the tool at the tip of a tool body, a counter boring part 39 to coincide a deviated center of gravity with an axis O is formed in a tip surface 37 of the tool body 23 in a state to be deviated from the axis O, and a lead run-off 41 to coincide the deviated center of gravity with an axis O is formed in the peripheral edge of the tip surface of the tool body 23 by chamfering deviated from the axis O, and a recessed part 5 to coincide the deviated center of gravity with the axis O is formed in the outer peripheral surface of a tool body approximately on the reverse side to the chip discharge groove 25 with the axis O nipped therebetween. <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. 6 and 7, on the outer periphery 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-blade hole drilling tool, a chip discharge groove is provided on the outer periphery of the tool body, and the cutting blade is attached to the inner wall surface of the chip discharge groove. Since the cutting force is applied to the cutting pad to stabilize the cutting, 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. This is particularly noticeable during high-speed cutting that improves cutting efficiency, and when cutting is performed with poor rotational balance, the sliding contact torque increases, causing a decrease in hole accuracy and galling and seizure. . 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 an eccentric center of gravity with the axis line. Part is formed eccentrically with the axis on the tip surface of the tool body, and a lead relief part for aligning the eccentric center of gravity with the axis is chamfered with the axis on the edge of the tip surface of the tool body. Is formed on the outer peripheral surface of the tool body on the side substantially opposite to the chip discharge groove sandwiching 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, the lead escape portion and the concave portion, Good rotation balance. And
Since the lead escape portion cuts the outermost periphery of the tool body, the center of gravity that is effectively eccentric with a small amount of cut volume can coincide with the axis line, and by providing the lead escape portion,
It is possible to suppress the volume of the counterbore portion to be small, and to prevent a decrease in strength of the tip portion of the tool body due to an increase in the inner diameter and the depth of the counterbore portion. Furthermore, since the recess also cuts the outermost periphery of the tool body, the eccentric center of gravity can be effectively aligned with the axis with a small cutting volume, and in addition, machining can be performed without interfering with the cutting edge. Therefore, even if the counterbore part and the lead relief part are formed and this concave part is formed even after the cutting edge is attached, the position of the center of gravity can be finely adjusted, and the counterbore part and the lead relief part are formed. The minute deviation between the center of gravity and the axis caused by the machining accuracy of (3) can be easily removed, and the center of gravity can be aligned with the axis more accurately.

A hole drilling tool according to a second aspect of the invention is the hole drilling tool according to the first aspect, characterized in that the recess extends in a direction along the axis.

In this hole drilling tool, since the recess is elongated in the direction along the axis, the amount of local cutting at any position in the circumferential direction increases. In addition, the concave portion has an oval shape whose opening is closed by the outer peripheral surface of the tool body, so when the outer peripheral surface of the tool body contacts the inner peripheral surface of the processing hole, the internal space becomes a closed space and also functions as a pocket for collecting the invading refrigerant. It also becomes effective in preventing galling and seizure. Further, in this case, since the concave portion extends in the axial direction, the concave portion contacts the inner peripheral surface in the depth direction of the machined hole in the longitudinal direction, and the refrigerant accumulated in the concave portion is supplied to the inner peripheral surface of the machined hole in a wide range.

A hole drilling tool according to a third aspect of the present invention is the hole drilling tool according to the first aspect, characterized in that the recess extends in the circumferential direction of the outer peripheral surface of the tool body in an elongated shape.

In this hole drilling tool, since the concave portion is elongated in the circumferential direction of the outer peripheral surface of the tool main body, the total length of the tool main body is limited, and even when a long concave portion along the axis of the tool main body cannot be formed, It becomes possible to form a recess. Also, since the recess is elongated in the circumferential direction of the outer peripheral surface of the tool body, even when a relatively thin workpiece is drilled, the recess opening contacts the inner peripheral surface of the drilled hole to seal it. Then, similarly to the above, it functions as a refrigerant reservoir pocket.

A hole drilling tool according to a fourth aspect is the hole drilling tool according to the second or third aspect, wherein the bottom surface of the recess is a circular arc curve in which the central portion is recessed in a vertical cross section in the longitudinal direction of the recess. Characterize.

In this hole drilling tool, a groove milling cutter which rotates on a rotary shaft in a direction orthogonal to the axis of the tool main body is used, and the outer peripheral surface of the tool main body is cut by a cutting blade provided on the outer peripheral surface of the groove milling cutter. Thus, it becomes possible to easily form a concave portion which is elongated in the axial direction of the tool body and whose bottom surface has an arc curve. In addition, a groove milling cutter that rotates on the rotating shaft in the same direction as the axis of the tool body is used, and the outer peripheral surface of the tool body is cut by the cutting edge provided on the outer peripheral surface of this groove milling, so that it is elongated in the circumferential direction. It is possible to easily form a concave portion having a curved bottom surface.

[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, FIG. 2 is a front view of the hole drilling tool shown in FIG. 1, FIG. 3 is a view taken along the line AA of FIG.
FIG. 4 is a side view showing a modification of the hole drilling tool shown in FIG.
FIG. 5 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.

Further, the lead escape portion 4 for aligning the eccentric center of gravity with the axis O is provided on the peripheral edge of the tip surface 37 of the tool body 23.
1 is formed. The lead escape portion 41 is provided in the tool body 23.
Can be formed by chamfering that is eccentric to the axis O on the peripheral edge of the tip surface of the. The lead escape portion 41 can be formed at an arbitrary position within the range shown by hatching in FIG. The spot facing portion 39 and the lead relief portion 41 are preferably processed before the cutting blade 29 is attached, but the lead relief portion 41 is particularly preferable.
May be formed by polishing after the cutting blade 29 is attached.

The lead escape portion 41 may be formed by chamfering in the circumferential direction as described above, or may be formed by chamfering a part of the peripheral edge of the chip discharge groove 25 sandwiching the axis O with a flat surface. In this case, the lead relief portion chamfered with a flat surface is formed on the tip end surface 37 of the tool body 23 by the chain double-dashed line 43 in FIG.
Appears in. In the lead relief portion chamfered with such a flat surface, as compared with the case where the lead relief portion 41 is formed with an eccentricity, a part of the peripheral edge may be chamfered with a flat surface, so that the lead relief portion 41 can be easily formed, and the cutting amount can be reduced. , It is possible to increase locally at any position in the circumferential direction.

The lead relief portion chamfered in such a plane is formed by chamfering after the spot facing portion 39 is formed, whereby the position of the center of gravity can be further adjusted.
The deviation between the center of gravity and the axis O caused by the processing accuracy of the spot facing portion 39 is easily removed, and the center of gravity is more accurately determined along the axis O.
Will be able to match.

Further, a concave portion 45 is formed on the outer peripheral surface of the tool body substantially opposite to the chip discharge groove 25 sandwiching the axis O so that the eccentric center of gravity coincides with the axis O. The recess 45 can be formed to be elongated in the direction along the axis O, as shown in FIG. Since the recess 45 is elongated in the direction along the axis O, the amount of local ablation at any position in the circumferential direction increases. In the illustrated example, one recess 45 is shown, but the recess 45 may have a plurality of parallel widths, depths, and lengths that are parallel to each other.

Since the recess 45 has an oval shape whose opening is closed by the outer peripheral surface of the tool body, when the outer peripheral surface of the tool body comes into contact with the inner peripheral surface of the machining hole, the internal space becomes a closed space, which is used for cooling the cutting edge described later. After the refrigerant is once discharged, it also functions as a pocket that collects along the outer peripheral surface of the tool body and is effective in preventing galling and seizure. Further, in this case, since the concave portion 45 extends in the axial direction, the concave portion 45 contacts the inner peripheral surface in the depth direction of the machining hole in the longitudinal direction, and the refrigerant accumulated in the concave portion 45 is supplied to the inner peripheral surface of the machining hole in a wide range. Will be done.

The recess is formed in a slender shape in the direction along the axis O as described above, and as a modification thereof, as shown in FIGS. 4 and 5, in the circumferential direction of the outer peripheral surface of the tool body. It may be formed to be elongated. Recess 4 in this case
7 has a restriction on the total length of the tool body 23,
Even when the long concave portion 45 along the axis O of can not be formed, it can be formed. Further, since the recess 47 is elongated in the circumferential direction of the outer peripheral surface of the tool body, even when a relatively thin work piece is drilled, the recess opening contacts the inner peripheral surface of the drilled hole. It is hermetically sealed and, like the above, functions as a refrigerant reservoir pocket. In addition, even in the case of the concave portion 47, although one is shown in the illustrated example, the concave portion 47 has a plurality of parallel portions of arbitrary width, depth and length in the direction orthogonal to the axis O. You may form.

These recesses 45, 47 have bottom surfaces 45a,
As shown in FIGS. 3 and 5, 47a is a vertical cross section in the longitudinal direction of the recess (a cross section in the groove depth direction), which is an arc curve in which the central part is recessed. As a result, for example, the concave portion 45 has the bottom surface 4
Since 5a is an arc curve, a groove milling cutter having a rotary shaft orthogonal to the axis O of the tool body 23 is used, and the tool body outer peripheral surface is cut by a cutting blade provided on the outer peripheral surface of the groove milling cutter. It is slender in the axial direction of the tool body 23, and the bottom surface 45a can be easily formed into an arc curve. Also, the recess 47
Is a groove milling cutter that rotates on a rotary shaft in the same direction as the axis O of the tool body 23, and the outer peripheral surface of the tool main body is cut by a cutting blade provided on the outer peripheral surface of the groove milling cutter, so that The bottom surface 47a is elongated and can be easily formed as an arc curve. The bottom surface is preferably a circular arc curve of a perfect circle as in the present embodiment, but may be another curve or a straight line.

The tool body 23 has a coolant supply passage 51 for supplying a coolant such as oil to the cutting location. The coolant supply passage 51 is bored in a direction along the axis O (coaxial with the axis O in the present embodiment). This refrigerant supply passage 51
The tip end of is open at the bottom portion 53 of the spot facing portion 39. Further, in the tool body 23, a coolant supply branch passage 55 having a larger inner diameter than the coolant supply passage 51 and opening toward the cutting edge 29.
Are communicated with the refrigerant supply passage 51 and are drilled. The refrigerant supply branch passage 55 has a predetermined inclination angle with respect to the axis O and extends outward in the radial direction of the tool body 23.

By piercing the refrigerant supply branch passage 55, a small diameter refrigerant supply passage 5 extending along the axis O is formed.
Due to the centrifugal force generated by the rotation of the tool main body 23, the refrigerant flowing through No. 1 flows radially outward from the refrigerant supply passage 51 toward the cutting edge 29 and flows into the large diameter refrigerant supply branch passage 55. As a result, the centrifugal force effectively acts, the refrigerant is diffused in the large-diameter refrigerant supply branch passage 55, and the refrigerant is evenly (to every corner) supplied to the cutting edge 29.

Further, it is preferable that the inner peripheral surface of the spot facing portion 39 is formed by a tapered surface 57 whose diameter increases toward the tip of the tool body 23. In this way, if the inner peripheral surface of the spot facing portion 39 is formed by the taper surface 57, the diameter of the taper surface 57 increases toward the tip, so that the chips that try to enter the inside of the spot facing portion 39 are formed. Force acts toward the tip,
It becomes difficult for the chips at the tip of the tool body to enter the counterbore 39. This makes it 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 forms the spot facing portion 39, the lead escape portion 41 and the recess 45 (or recess 47). By this, the axis O of the tool body 23, that is, the center of rotation, coincides, and the rotation balance becomes good. Since the lead escape portion 41 cuts the outermost periphery of the tool body 23, the eccentric center of gravity is effectively aligned with the axis with a small cut volume, and the lead escape portion 41 is provided side by side. The volume of the spot facing portion 39 can be suppressed to be small, and the strength reduction of the tip end portion of the tool body due to the increase in the inner diameter and the depth of the spot facing portion 39 is prevented.

Further, since the concave portion 45 (or the concave portion 47) also cuts the outermost periphery of the tool body 23, the eccentric center of gravity effectively coincides with the axis O with a small cutting volume.
In addition to this, since machining can be performed without interfering with the cutting edge 29,
The spot facing portion 39 and the lead escape portion 41 are formed, and the cutting edge 2
Even after 9 is attached, the position of the center of gravity can be finely adjusted by forming the recess 45 (or the recess 47), which is caused by the processing accuracy of the counterbore 39 and the lead escape 41. A minute deviation between the center of gravity and the axis O can be easily removed, and the center of gravity can be aligned with the axis O with higher accuracy.

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.

[0030]

As described above in detail, 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 is provided on the tip surface of the tool body. And the eccentric center of gravity are formed on the peripheral edge of the tip end of the tool body by chamfering eccentric to the axis, and the eccentric center of gravity is aligned with the axis. Since the matching recesses are formed on the outer peripheral surface of the tool body on the side substantially opposite to the chip discharge groove that sandwiches the axis, the center of gravity that is eccentric due to the chip discharge groove and the cutting blade is reduced by the spot facing, the lead escape, and the recess. With the formation of, the axis of the tool body, that is, the center of rotation, can be matched, and the rotation balance can be improved. Since the lead escape portion cuts the outermost periphery of the tool body, it is possible to effectively align the eccentric center of gravity with the axis with a small amount of cut volume. It is possible to suppress the volume of the tool to be small and prevent the strength of the tip portion of the tool body from being lowered due to the increase in the inner diameter and the depth of the counterbore. Furthermore,
Since the recess also cuts the outermost circumference of the tool body, it is possible to effectively align the eccentric center of gravity with the axis with a small cutting volume, and it is possible to process without interfering with the cutting edge. Even after the boring part and the lead relief part are formed and the cutting edge is attached, the position of the center of gravity can be finely adjusted by forming this concave part, depending on the machining accuracy of the spot facing part and the lead relief part. It is possible to easily remove the minute deviation between the center of gravity and the axis line that has occurred, and to align the center of gravity with the axis line with higher accuracy. In other words, the center of gravity can be adjusted in stages (from the spot facing to the lead escape and recesses) to a position where slight adjustment is possible, enabling extremely highly accurate adjustment. can do. 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 concave portion is formed so as to be elongated in the direction along the axis, the local cutting amount at any position in the circumferential direction is increased. can do. Further, since the recess has an oval shape in which the opening is closed by the outer peripheral surface of the tool body, when the outer peripheral surface of the tool body contacts the inner peripheral surface of the processing hole, the internal space becomes a closed space,
It also functions as a pocket for storing the invading refrigerant, which is effective in preventing galling and seizure. Further, in this case, since the concave portion extends in the axial direction, the concave portion is in contact with the inner peripheral surface in the depth direction of the machining hole in the longitudinal direction, and the refrigerant accumulated in the concave portion can be supplied to the inner peripheral surface of the machining hole in a wide range. it can.

According to the hole drilling tool of the third aspect, since the concave portion is formed so as to be elongated in the circumferential direction of the outer peripheral surface of the tool body, there is a restriction on the total length of the tool body. It is effective when a long recess along the axis of the main body cannot be formed. Also, since the recess is elongated in the circumferential direction of the outer peripheral surface of the tool body, even when drilling a relatively thin workpiece, the recess opening must be in contact with the inner peripheral surface of the machined hole to seal it. It is possible to function as a refrigerant reservoir pocket in the same manner as described above.

According to the hole drilling tool of the fourth aspect, the bottom surface of the concave portion is a circular arc curve in which the central portion is concave in the longitudinal cross section in the longitudinal direction of the concave portion, so that the tool is rotated about the axis of rotation of the tool body. By using a groove milling machine that cuts, and by cutting the outer peripheral surface of the tool body with a cutting blade provided on the outer peripheral surface of this groove milling tool, a recess that is elongated in the axial direction of the tool body and has a curved bottom surface can be easily formed. By using a groove milling cutter that rotates on the rotating shaft in the same direction as the axis, and cutting the outer peripheral surface of the tool body with the cutting edge provided on the outer peripheral surface of this groove milling, it is easy to make a recess that is elongated in the circumferential direction and has an arc curved bottom surface. Can be formed into

[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 view on arrow AA of FIG.

FIG. 4 is a side view showing a modified example of the hole drilling tool shown in FIG. 1.

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

FIG. 6 is a side view of a conventional hole drilling tool.

FIG. 7 is a front view of the hole drilling tool shown in FIG. 6.

[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 ... Lead escape area 45, 47 ... Recess 45a, 47a ... Bottom of recess 51 ... Refrigerant supply passage 55 ... Refrigerant supply branch 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 rotating around the axis, and an inner wall surface of the chip discharge groove facing the tool rotation direction at the tip of the tool body. In a hole drilling tool having a cutting edge attached to, a counterbore portion for aligning an eccentric center of gravity with the axis is formed on the tip surface of the tool main body with the axis eccentric, and
A lead relief part that matches the eccentric center of gravity with the axis,
An outer peripheral surface of the tool body on the opposite side of the chip discharge groove sandwiching the axis is formed with a concave portion formed on the peripheral edge of the tip surface of the tool body by chamfering eccentric with the axis, and having an eccentric center of gravity aligned with the axis. A hole drilling tool characterized by being formed on. 2. The hole drilling tool according to claim 1, wherein the recess extends in a slender shape in a direction along the axis. 3. The hole drilling tool according to claim 1, wherein the recess extends in an elongated direction in a circumferential direction of the outer peripheral surface of the tool body. 4. The hole drilling tool according to claim 2 or 3, wherein the bottom surface of the recess is a circular arc curve with a recess at the center in a longitudinal cross section in the recess longitudinal direction.