JP2000198009A - Throw-away type drilling tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of machining precision without swinging of a tool main body at the time of chamfering of a cutting edge even in the case of applying drilling work on a groove a cross section of which makes a recessed curve or a bottom surface of a recessed part on a drilling tool on a tool head end outer peripheral side and an inner peripheral side of which cutting edge tips are arranged biased. SOLUTION: A first outer peripheral side cutting edge tip 13 furnished with a cutting edge 19 on one side with an axis ○ inbetween of which an outer peripheral end is projected to an outer periphery of a tool main body 1 is installed on a head end of the tool main body 1 to be rotated around the axis ○free to connect and disconnect to and from it. Additionally, on the other side with the axis ○inbetween, an inner peripheral side cutting edge tip 14 furnished with the cutting edge 19 an inner peripheral end of which reaches the axis ○ and a second outer peripheral side cutting edge tip 15 furnished with the cutting edge 19 an outer peripheral end of which is projected to the outer periphery of the tool main body 1 are installed free to connect and disconnect to and from it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away type drilling tool (hereinafter referred to as a "hole") in which a cutting edge tip is mounted on the tip of a tool main body so as to be biased toward the outer peripheral side and the inner peripheral side with respect to the axis thereof. This is referred to as a “drilling tool.”

[0002]

2. Description of the Related Art A drilling tool of this kind is disclosed in Japanese Utility Model Laid-Open Publication No. 54-88992, and in
Japanese Patent Application Laid-Open No. 150304/1999 discloses that an outer peripheral cutting edge tip which is arranged at a tip mounting seat formed at a tip end of a tool body rotated about an axis and which is biased toward an outer peripheral side of a tool, has the same shape as the outer peripheral cutting edge tip. An inner peripheral side cutting edge tip having the same shape and arranged eccentrically toward the inner peripheral side of the tool is mounted on the opposite side with respect to the axis. However, in these drilling tools, the outer peripheral side cutting edge tip projects the outer peripheral end of the cutting edge toward the outer peripheral side of the tool body, and the inner peripheral side cutting edge tip has the inner peripheral end of the cutting edge. It is arranged so as to reach the axis, and the rotation trajectories around the axis of these cutting edges are made to intersect each other, so that a hole having an inner diameter equal to or longer than the cutting edge length of a single cutting edge tip can be drilled. At the same time, by balancing the radial components of the cutting load acting on the inner and outer peripheral cutting edges, it is possible to suppress the runout of the tool body during drilling.

[0003]

However, the situation is different when such a drilling tool is used to drill a groove or a concave surface having a concave curved section such as a concave arc in cross section. Becomes That is, when performing drilling on the bottom surface of such a groove or a concave portion, when the tool body is rotated around its axis and feed is applied to the front end side in the axial direction to try to bite the cutting edge, Even if the position of the peripheral cutting edge tip in the axial direction of the cutting edge is the same, the distance between the cutting edge and the bottom surface of the groove or recess increases toward the inner peripheral side of the tool body, so the outer peripheral cutting edge The outer peripheral end of the cutting edge of the insert will first bite into the bottom surface, and the impact load at this time causes the tool body to be largely shaken to the side opposite to the side where the outer peripheral side cutting edge chip is mounted, As a result, processing accuracy such as roundness and straightness of a processing hole is deteriorated.

[0004] The present invention has been made in view of such circumstances, and in a drilling tool in which the cutting edge tip is arranged eccentrically on the outer peripheral side and the inner peripheral side of the tool tip, the above-described groove or recess is provided. It is an object of the present invention to provide a drilling tool capable of preventing the tool body from swinging when the cutting edge bites even when drilling is performed on the bottom surface of the cutting tool, and capable of preventing deterioration of the processing accuracy.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve such an object, the present invention provides a tool body rotated around an axis at one end with the axis interposed therebetween. A first outer peripheral side cutting edge tip having a cutting edge whose outer peripheral end protrudes to the outer periphery of the tool body is detachably mounted, and an inner peripheral end is provided on the other side across the axis. An inner peripheral cutting edge tip provided with a cutting edge reaching the axis, and a second outer peripheral cutting edge tip provided with a cutting edge having an outer peripheral end protruding to the outer periphery of the tool body are detachably mounted. And
Therefore, according to such a drilling tool, even when the cutting edge is made to bite into the bottom surface of the groove or the concave portion whose cross section is concave as described above, they are arranged on the opposite sides with respect to the axis of the tool main body. Since the first and second outer peripheral side cutting tips bite at the same time on the bottom surface to offset the radial load, it is possible to prevent the tool main body from oscillating at the time of the biting. .

Here, on one side of the tool body to which the first outer peripheral cutting tip is mounted, the configuration is different from that of the conventional drilling tool on which the outer peripheral cutting tip is mounted. No, it is possible to appropriately set the tip shape and the like according to the specifications. On the other side, the inner peripheral side cutting edge tip is formed in a substantially equilateral triangular flat plate shape, and the triangular surface thereof is formed. It is preferable that the cutting edge is formed on the side ridge, and that the corner of the triangular surface facing the side ridge is mounted on the rear end side of the tool and mounted. The thickness of the wall surface of the tip mounting seat on which the peripheral cutting edge tip is mounted can be increased to secure the mounting rigidity.

At least the second outer peripheral cutting edge tip is formed in a substantially rhombic flat plate shape, the cutting edge is formed at a side ridge of the rhombic surface, and one end connected to the side ridge is formed. Along with projecting the acute-angled corner as the outer peripheral end to the outer periphery of the tool main body, the other acute-angled corner facing the one acute-angled corner is located at the rear end side of the tool inner periphery and mounted. It is preferable that a load acting toward the radially inner peripheral side when the second outer peripheral cutting edge bites into the bottom surface is applied to the tip mounting seat to which the inner peripheral side cutting edge tip is mounted. Of the wall surfaces, the pair of wall surfaces abutting the chip side surfaces sandwiching the other acute angle portion can surely receive the chip.

[0008]

FIG. 1 to FIG. 6 show an embodiment of the present invention. In the present embodiment, the tool main body 1 has a substantially multi-stage cylindrical shape having a truncated cone-shaped flange portion 2 formed at a substantially central portion in the direction of the axis O, and the tool tip side (refer to FIG. Left side) Blade 3
At the same time, the rear end side of the tool (right side in FIG. 1) is formed as a shank portion 4. The shank portion 4 is mounted on a main shaft or the like of a machine tool to rotate around the axis O in the tool rotation direction T. Then, a feed is given to the tool tip side in the direction of the axis O to perform drilling of the work material. A supply hole 5 for cutting oil or the like is formed along the axis O from the shank portion 4 toward the tool tip.
Is branched into two on the tip end side of the tool, and are respectively opened at tip end flank surfaces 6 and 6 at the tip end of the tool body 1. Another supply hole 7 communicating with the supply hole 5 is formed on the outer periphery of the flange portion 2.
Is used when a drilling process is performed by gripping the drilling tool on a tool rest or the like of a machine tool like a bite and rotating a work material. Has been stopped.

On the outer periphery of the blade portion 3 of the tool body 1, from the front flank surfaces 6, 6 to the flange portion 2, toward the rear end side of the tool, toward the rear side in the tool rotation direction T. A pair of chip discharge grooves 9, 9 twisted around the axis O
Are formed on the opposite sides with respect to the axis O. Of these chip discharge grooves 9, 9, the chip discharge grooves 9 on one side are formed.
On the wall surface 9A of the tip of the lower chip discharge groove 9 in FIG. 2 facing the tool rotation direction T, one chip mounting seat 10 is provided on the outer peripheral side of the tool, and the other chip discharge groove 9 ( In FIG. 2, a pair of chip mounting seats 11 and 12 are formed on the inner and outer peripheral sides of the tool, respectively, on the wall surface 9A facing the tool rotation direction T at the tip of the upper chip discharge groove 9).
Among these tip mounting seats 10 to 12, a first outer peripheral cutting edge tip 13 is mounted on the tip mounting seat 10 on one side, and the tip mounting seat 11 on a tool inner circumference side on the other side. And a second outer peripheral cutting tip 15 is detachably attached to the tip mounting seat 12 on the outer peripheral side of the tool on the other side by a clamp screw 16. . In the present embodiment, as shown in FIG. 1, the blade 3 is formed such that its outer diameter is slightly increased one step at a substantially central portion of the blade 3 in the direction of the axis O.

Here, the tip mounting seats 10 to 12 are
Bottom surfaces 10A to 12A each formed to retreat one step backward in the tool rotation direction T with respect to the wall surface 9A.
And the wall surface 9A rising from the bottom surfaces 10A to 12A.
The bottom surface 10A has a substantially rhombic shape, the bottom surface 10B has a substantially regular triangle shape, and the bottom surface 10C has a concave shape defined by a pair of wall surfaces 10B to 12B and 10C to 12C.
Is formed in a diamond shape which is slightly smaller than the bottom surface 10A, and a screw hole (not shown) into which the clamp screw 16 is screwed is formed in each of the bottom surfaces 10A to 12A, and the wall surfaces 10B to 12B and the wall surfaces 10C to 12C are formed.
Is a V of approximately 60 ° when viewed from the direction facing the wall surface 9A.
It is formed in a letter shape. Note that the wall surfaces 10B, 12B and the wall surfaces 10C, 12C of the tip mounting seats 10, 12 on which the first and second outer peripheral side cutting blade tips 13, 15 are mounted.
Means that the V-shaped bisector formed by these is formed so as to extend obliquely toward the outer periphery of the tool tip with respect to the axis O, while the inner peripheral cutting tip 14 is attached. The wall surfaces 11B and 11C of the chip mounting seat 11
The bisector of the character is formed so as to be substantially parallel to the axis O, or to extend slightly toward the outer peripheral side of the tool tip.

In the present embodiment, the cutting edge tips 13 to 15 attached to the tip attachment seats 10 to 12 are positive tips made of a hard material such as a cemented carbide, and are first and second. Outer peripheral side cutting tip 13,
Reference numeral 15 denotes a substantially rhombic flat plate having a pair of acute corners 17 and 17 at 60 °, while the inner peripheral cutting edge tip 1 is formed.
Numeral 4 is formed in a substantially equilateral triangular flat plate shape, and one of the rhombic surfaces or equilateral triangular surfaces is a rake face 18 and cutting edges 19 are provided at each side ridge of the one rhombic surface or equilateral triangular surface. Is formed. However, the cutting edges 19 are bent at the pair of corners 17, 17 of the first and second outer peripheral cutting edges 13, 15 and at the corners 20... Of the inner peripheral cutting edge 14. It is formed so as to be bent one step at an obtuse angle at a point 21. Further, the second outer peripheral side cutting tip 15 is made one size smaller than the first outer peripheral side cutting edge tip 13, and the inner peripheral side cutting edge tip 14 has a length of the one side ridge portion. The first and second outer peripheral side cutting edges 13 and 15 have a middle length of the length of the side ridges. Further, a chip breaker groove 22 is formed along the cutting edge 19 on the outer peripheral edge of the rake face 18 of each of the cutting edge chips 10 to 12.

The first and second outer peripheral cutting tips 13 and 15 are respectively connected to the tip mounting seats 10 and 12.
Then, the rake face 18 is directed toward the tool rotation direction T, and the one corner 17 is protruded toward the outer periphery of the tool, and the one cutting edge 19 connected to the corner 17 is directed toward the tip of the tool.
Further, the lower surface opposite to the rake surface 18 is
A, 12A, and the other corner 17 opposite to the one corner 17 is positioned on the inner peripheral side of the rear end of the tool. The wall 10
B, 10C or the wall surfaces 12B, 12C are seated in contact with each other, and are fixed by clamp screws 16. Also,
The inner peripheral side cutting edge tip 14 has the rake face 18 facing the tool mounting direction T side, the one cutting edge 19 facing the tool tip side, and the cutting edge 19.
The one corner 20 which is the end on the tool inner peripheral side of the wall surface 9A
As shown in FIG. 5, when viewed from the direction opposite to the front surface, the tool is positioned on the first outer peripheral cutting edge tip 13 side beyond the axis O of the tool main body 1, and the lower surface opposite to the rake face 18 is located on the bottom surface 1.
1A, the other corner 20 facing the one cutting edge 19 is positioned on the rear end side of the tool, and the side surface of the other corner 20 is brought into contact with the wall surfaces 11B and 11C. It is seated in contact, and is fixed by the clamp screw 16.

Here, in each of the cutting edge chips 13 to 15 attached in this manner, one of the cutting edges 19 directed to the respective tool tip side is the one of the above-mentioned one corner portion 17,2.
The bend point 21 on the 0 side is disposed so as to protrude most toward the front end of the tool, and has a mountain shape that is directed from the bend point 21 toward the rear end of the tool toward the inner and outer peripheral sides of the tool. The bending points 21 of one of the cutting edges 19 of 12 to 15 are arranged so that their positions in the direction of the axis O coincide with each other. Further, the outer diameter of the first cutting edge 19, 19, that is, the rotation diameter of the one corner portion 17, 17 around the axis O is the same as the first and second outer peripheral cutting edges 13, 15, respectively. And the first outer peripheral cutting edge tip 1
The rotation locus of the one cutting edge 19 around the axis O includes the rotation locus of the one cutting edge 19 of the second outer peripheral cutting tip 15 in the radial direction with respect to the axis O, and
The one cutting edge 19 of the outer peripheral side cutting edge tip 13 and the one cutting edge 19 of the inner peripheral side cutting edge tip 14 are arranged so that their rotation trajectories around the axis O cross each other.

However, in the drilling tool configured as described above, not only is a drilling process performed on a flat surface perpendicularly, but also a hole is formed on a bottom surface of a groove or a concave portion having a concave cross section as described above. Even when machining is performed, the first outer peripheral cutting edge tip 13 is attached to one side of the tip of the tool main body 1, while the second outer peripheral cutting edge tip 15 is mounted on the other side. Are attached, and one of the cutting edges 19, 19 facing the tool tip side of the outer peripheral cutting tips 13, 15.
19 will simultaneously bite into the bottom surface of the groove or recess. Therefore, the impact load acting on the tool main body 1 at the time of biting is such that the radial component thereof is evenly applied to the first and second outer peripheral side cutting blade tips 13 and 15 and the inner side of the tool with the axis O interposed therebetween. Since they act in opposite directions and cancel each other out, the tool body 1 does not run out when biting, and thereafter the inner peripheral side cutting edge tip 14 is moved with the feed of the tool body 1. The one cutting edge 19 also bites into the bottom surface, and its rotation locus around the axis O continuously drills a processing hole with the first outer peripheral cutting edge tip 13. For this reason, according to the drilling tool having the above-described configuration, even when the cutting blade tips 13 to 15 are attached to the tip of the tool main body 1 in a radial direction,
In the drilling of the grooves and recesses, it is possible to prevent processing accuracy from being impaired due to run-out at the time of biting, and it is possible to form a processing hole with high roundness and straightness.

By the way, in such a drilling tool, the length of the chips generated by the cutting blades 19 while the tool body 1 makes one rotation around the axis O depends on the difference in the rotation diameter from the axis O. Since the outer peripheral side of the tool is longer than the inner peripheral side of the tool, the chips on the outer peripheral side of the tool tend to grow, which may hinder chip processing. On the other hand, in the drilling tool having the above configuration, the first and second pair of outer peripheral side cutting blades 13 and 15 are attached to the outer peripheral side of the tool, so that the chips are divided into two in the circumferential direction. Will be generated. Therefore, according to the drilling tool having the above-described configuration, it is possible to reliably cut and process chips on the outer peripheral side of the tool, which tend to be slightly stretched as described above, and the chips are clogged and smooth drilling is performed. The effect of preventing such a situation can also be obtained.

On the other hand, in the present embodiment, the inner peripheral side cutting edge tip 14 is formed in a substantially equilateral triangular flat plate shape, and one triangular surface is used as the rake face 18 and the rake face 18
A cutting edge 19 is formed on one of the side ridges, and the inner peripheral side cutting tip 14 is used to perform a drilling operation on the cutting edge 19 formed on the one side ridge toward the tool tip side. At the same time, the other corner 20 of the rake face 18 facing the one side ridge is located on the tool rear end side and attached to the tip mounting seat 11. Therefore, according to the present embodiment, the wall surfaces 11B and 11C of the tip mounting seat 11 holding the inner peripheral side cutting edge tip 14 have their bisectors substantially parallel to the axis O or slightly as described above. It is formed in a V-shape extending toward the outer periphery of the tool tip,
Between the wall surface 11B of the tip mounting seat 11 facing the tool inner peripheral side and the wall surface 12B of the tip mounting seat 12 to which the second outer peripheral cutting edge tip 15 is mounted facing the tool outer peripheral side, and the tool of the tip mounting seat 11 A large wall thickness can be secured toward the tool rear end between the wall surface 11C facing the outer peripheral side and the wall surface 9B facing the tool rotation direction T rear side of the chip discharge groove 9 on the one side. By improving the mounting rigidity of the inner peripheral side cutting blade tip 14, more stable drilling can be promoted.

Further, in the present embodiment, the first and second
The outer peripheral side cutting edge chips 13 and 15 are formed in a substantially rhombic flat plate shape, one of the rhombic surfaces is a rake face 18, and one of the cuts formed on the side ridge of the rake face 18 is formed. Blade 1
9 is directed toward the tool tip, one acute-angled corner 17 continuous with the side ridge is projected toward the tool outer peripheral side, and another acute-angled corner 17 facing the one corner 17 is formed. It is attached to the tip mounting seats 10 and 12 so as to be located on the inner peripheral rear end side of the tool. The two side surfaces on the other corner 17 side are in contact with the wall surfaces 10B, 10C and the wall surfaces 12B, 12C of the V-shaped tip mounting seats 10, 12 facing the outer peripheral side of the tool tip. According to the present embodiment, since the cutting blade tips 13 and 15 are fixed, these first and second cutting tips 13 and 15 are fixed.
Even when an impact load acts on the inner peripheral side of the tool as described above when the second outer peripheral cutting edges 13 and 15 bite into the work material, the impact is applied to the V-shaped wall surface 10B. , 10C and the wall surfaces 12B, 12C so that the tool body 1 can be more reliably prevented from running out due to such a load.

In this embodiment, both the first and second outer peripheral cutting tips 13 and 15 are formed in a rhombic flat plate shape as described above. In order to intersect the rotation locus of the one cutting edge 19 facing the tool tip with the rotation locus of the one cutting edge 19 of the inner peripheral side cutting edge tip 14, the size of the second outer peripheral portion is naturally determined. The cutting edge must be larger than the side cutting edge tip 15, and accordingly, the chip mounting rigidity can be more easily secured than the second outer peripheral side cutting edge tip 15. Without being formed in the shape, for example, it may be a substantially equilateral triangular flat plate shape as in the case of the inner peripheral side cutting edge tip 14, or may be another shape. This also applies to the second outer peripheral cutting edge tip 15 in some cases. Further, in the present embodiment, the blade portion 3 is formed such that its diameter is increased by one step at the center thereof, whereby the rigidity of the blade portion 3 can be improved particularly in a drilling process in which the tip side of the blade portion 3 is frequently used. Is secured to further prevent the tool body 1 from oscillating, but the blade portion 3 may be formed to have a uniform outer diameter over its entire length without adopting such a configuration.

[0019]

As described above, according to the present invention,
When drilling the bottom surface of a groove or a concave portion having a concave cross section, a drilling tool in which a cutting edge tip is arranged at the tip of the tool main body so as to be biased toward the inner circumferential side and the outer circumferential side of the tool. However, it is possible to prevent run-out of the tool main body when the cutting edge bites, and to prevent deterioration in machining accuracy such as roundness and straightness of a machined hole.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is an enlarged front view of the embodiment shown in FIG.

FIG. 3 is an enlarged side view as viewed in the direction of arrow A in FIG. 2;

FIG. 4 is an enlarged side view in the direction of arrow B in FIG. 2;

FIG. 5 is an enlarged side view as viewed in the direction of arrow C in FIG. 2;

FIG. 6 is an enlarged side view as viewed in the direction of arrow D in FIG. 2;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tool main body 3 Blade part 9 Chip discharge groove 10,11,12 Chip mounting seat 10A, 11A, 12A Chip mounting seat 10,11,1
2 Bottom surface 10B, 10C, 11B, 11C, 12B, 12C Wall surface of tip mounting seats 10, 11, 12 13 First outer peripheral side cutting edge 14 Inner peripheral side cutting edge tip 15 Second outer peripheral side cutting edge tip 16 Clamp screw 17 Sharp corners of the first and second outer peripheral cutting edges 13 and 15 18 Rake face 19 Cutting edge 20 Corners of the inner peripheral cutting edge 14 O Rotation axis of the tool body 1 T Tool body 1 Direction of rotation

Claims (3)

[Claims] 1. A first outer peripheral cutting edge provided with a cutting edge at one end of a tool main body that is rotated around an axis and having an outer peripheral end protruding to the outer periphery of the tool main body on one side with the axis interposed therebetween. A tip is detachably mounted, and on the other side of the axis, an inner peripheral side cutting edge tip having a cutting edge having an inner peripheral end reaching the axis, and an outer peripheral end being an outer periphery of the tool body. And a second outer peripheral side cutting edge tip having a cutting edge protruding from the cutting tool is detachably mounted. 2. The inner peripheral side cutting edge tip is formed in a substantially equilateral triangular flat plate shape, the cutting edge is formed on a side ridge of the triangular surface, and the triangle facing the side ridge. The indexable drilling tool according to claim 1, wherein a corner portion of the surface is mounted on the rear end side of the tool. 3. The second outer peripheral side cutting edge tip is formed in a substantially rhombic flat plate shape, the cutting edge is formed on a side ridge of the rhombic surface, and one end connected to the side ridge is formed. Along with projecting the acute corner of the tool body as the outer peripheral end to the outer periphery of the tool body, the other acute corner opposed to the one acute corner is located at the rear end side of the tool inner periphery and mounted. The indexable drilling tool according to claim 1 or 2, wherein the drilling tool is provided.