JP2003062712A - Tip of cutting edge for throw-away drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the processability of chips for the tip of a cutting edge for a throw-away drill which can be mounted as an outer peripheral edge or a central edge since it is formed into a substantially parallelogrammatic plate shape. SOLUTION: Heights from a cutting edge 3 on a rising wall 8 in a breaker groove 6 arranged on the top face of the tip 1 of the cutting edge are formed such that one side is gradually increased and the other side is gradually decreased as leaving a corner 2 with relation to two directions pinching the acute angular corner 2. The processability of chips in accordance with a material to be cut can be improved by selecting the enlargement or shortening of the height-changing direction since the height-changing directions on the rising wall 8 can be made similar even in the outer peripheral edge 13 or in the central edge 17 when this is incorporated into a drill 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting edge tip for a throw-away drill which has improved chip disposability in a breaker groove.

[0002]

2. Description of the Related Art As prior art, Japanese Patent Laid-Open No. 10-2639
A cutting edge tip for a throw-away drill disclosed in Japanese Patent Publication No. 05 is illustrated in FIG. The cutting edge tip 1 has a substantially parallelogrammatic plate-like appearance, and has a special shape in which a part of the cutting edge 3 is bent in a "F" shape in the vicinity of an acute-angled corner 2. The height of the cutting edge 3 from the bottom surface of the tip is
It is coordinated all around. A breaker groove 6 is provided on the upper surface along the entire circumference of the cutting edge 3, and its cross-sectional shape is constant regardless of the cross-sectional location as shown in FIG. That is, the breaker groove 6 has a narrow land 1 with a rake angle of 0 °.
8 and the height of the rising wall 8 from the cutting edge 3 is h
1 is formed.

As shown in FIG. 13, the cutting blade tip 1 is detachably attached to a tip seat cut out in a chip discharge groove 15 of a drill 12 by a tightening screw 19. The cutting edge tip 1 is arranged such that the bent point of the “F” shape is the tip point, and the long side 10 of the parallelogram shape is the bottom blade of the center blade 17, and the short side 9 is the bottom of the outer peripheral blade 13. Arranged as blades to form a series of bottom blades.

[0004]

Generally, a throw-away drill is constructed such that at least two cutting blade tips are incorporated, and each of them shares a bottom blade to form a series of bottom blades. At this time, since the chip forming mechanism is different between the center blade side having a low cutting speed and the outer peripheral blade side having a high cutting speed, the shape of the discharged chips is different. In the case of such a throw-away drill, chip disposal is more difficult on the outer peripheral edge side than on the central edge,
Conventionally, the breaker groove shape has been developed with an emphasis on chip disposal in the outer peripheral blade.

The shape of the conventional breaker groove as cited above is intended to promote chip deformation with the narrow land provided in contact with the cutting edge and the rising wall of the breaker. Therefore, if the cutting feed rate is low, the chips will easily get over the breaker, and conversely, if the feed rate is high, the chip thickness will be thick and deformation will not occur easily.Therefore, the cutting condition application area where the breaker groove functions well There is a problem that is narrow. In particular, it has high ductility like stainless steel and mild steel,
In a work material in which chips easily extend, the chip outflow direction changes sensitively according to changes in cutting conditions, so chip processing is difficult, and improvement of the breaker shape has been awaited.

If the respective cutting edge tips are not considered for sharing the outer peripheral blade and the central blade, the respective breaker grooves can be freely designed according to the cutting situation. However, the use of two different types of cutting blade tips has problems in terms of storage / management of cutting blade tips, workability of tip replacement, and cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a substantially parallelogrammatic plate shape, and has a thrower groove on its upper surface along which a breaker groove is provided. In the cutting edge tip for away drills, the height of the rising wall from the cutting edge of the breaker groove is with respect to two directions sandwiching an acute-angled corner, as the distance from the corner increases,
It is characterized in that one is gradually increased and the other is gradually decreased. Further, the rake face of the cutting edge tip is characterized by being formed into a regular angle by the breaker groove or the narrow land.

The cutting edge tip of the present invention is a cutting edge tip that can be used both as the outer peripheral edge and the center edge of a drill, and is capable of excellent chip disposal. There are two types of changes in the height of the rising wall of the breaker groove, and one of the bottom blades is that the height gradually decreases from the outer peripheral corner of the drill toward the rotation axis direction. The cutting edge tip of the present invention is characterized in that the height of the rising wall gradually decreases in the direction of the rotation axis even when it is mounted as a center blade after changing the corner. Such a shape of the breaker groove imparts a deformation toward the rotation axis of the drill to the chips in both the outer peripheral blade and the center blade.

[0008] By the way, for the work material in which the chips cannot be broken only by the breaker groove, a means of hitting the chips against the wall surface of the chip discharge groove of the drill to force the deformation can be considered. The present invention uses such a means, and aims to guide the chips to the wall surface by using the breaker groove as described above. The positive rake angle not only improves the sharpness, but also reduces the thickness of the chips to facilitate deformation, so that the chips are reliably guided to the wall surface.

The second change in the height of the rising wall of the breaker groove is such that it gradually increases in the direction of the rotation axis from the outer peripheral corner of the drill. In the present invention, the corner is changed. The feature of the center blade is that the height of the rising wall changes in the same manner. The shape of the breaker groove gives the chip a deformation that tends to extend in the direction parallel to the axis of rotation of the drill. For a work material for which chip treatment is not particularly important, or conversely, for a work material that is extremely difficult to handle regardless of the shape of the chip, the sharpness is improved and the chip is cut without aiming at unreasonable chip breaking. It has the function of smoothly sending out in the direction of the discharge groove.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment, in which a cutting edge tip 1 has a substantially parallelogrammatic plate-like appearance, and more specifically, in the vicinity of an acute-angled corner 2,
A part of the cutting edge 3 has a special outer shape that is bent in a "F" shape. The flank 4 has a clearance angle over the entire circumference to form a positive throwaway tip. The height of the cutting edge 3 from the lower surface of the tip is equidistant over the entire circumference. A countersunk hole is formed in the center of the cutting blade tip 1 to serve as a mounting hole 5 when screwed and fixed to the drill body. A breaker groove 6 is provided along the cutting edge 3 on the upper surface of the chip. In the breaker groove 6, minute projections 7 having a small height for reducing the frictional force with the chips are arranged at regular intervals. It is set up.

In this embodiment, as shown in FIG. 2, the height of the rising wall 8 of the breaker groove 6 with respect to the cutting edge 3 is such that the short side 9 of the parallelogram has a sharp corner. The height h1 near 2 is the highest, and the height h1 gradually decreases as the distance from the corner 2 increases, and the height h1 is formed at a constant height h2 from the middle portion. On the other hand, the long side of the parallelogram 1
On the 0 side, as shown in FIG.
The height h3 near the corner is the lowest, and the height h3 changes at the same height up to the middle part of the corner 2.
It is gradually increasing up to 4.

The rake face 11 in the breaker groove 6 is
As shown in this embodiment, in addition to being formed in a positive rake angle in contact with the cutting edge 3, a narrow land having a positive rake angle is interposed between the cutting edge 3 and the rake face 11. It may be done.

In FIG. 4, the cutting edge tip 1 is a drill 12
3 shows an outflow state of the chips 14 generated by the outer peripheral blade 13 when mounted on the. Cutting blade tip 1
Has a parallelogram-shaped short side 9 incorporated as a bottom blade. The chips 14 are guided to the rising wall 8 by being pulled inside the breaker groove 6 by the positive rake angle action. At this time, the chip 14 becomes thin due to the action of the rake angle, so that the chip 14 can be curved with a small force. Since the height of the rising wall 8 has a relationship of h1> h2, the chip 14 guided to the rising wall 8 is subjected to a deforming force that pushes it away in the rotation axis direction. As a result, the chips 14 collide with the wall surface 16 of the chip discharge groove 15 and are forcibly deformed, cracked, and broken.

FIG. 5 is a front view of the central blade 17 in FIG. A cutting edge tip 1 of the same shape is attached to a drill 12 with a parallelogram long side 10 as a bottom blade.
It is combined with the outer peripheral blade 13 to form a series of bottom blades. Even the chips 14 flowing out from the central blade 17 have the outer peripheral blade 13
As in the case of, the height of the rising wall 8 of the breaker groove 6 is h4.
Since there is a relation of> h3, deformation toward the rotation axis direction is added. Then, it collides with the wall surface 16 of the chip discharge groove 15, undergoes a forced deformation, and cracks and breaks.

The above chip treatment method is particularly suitable for drilling stainless steel, mild steel, low carbon steel or the like, which produces continuous chips and easily bends into bellows due to collision with the wall surface 16. However, since the chip 14 hits the wall surface 16 of the chip discharge groove 15 strongly and wears the drill body earlier than usual, it is preferable to take reinforcement measures in advance such as increasing the hardness of the part.

6 to 8 show the second embodiment, and the same parts as those described above are designated by the same reference numerals. The cutting edge tip 1 is different from the first embodiment in that the height relationship of the rising wall 8 of the breaker groove 6 is reversed. That is, the heights have a relationship of h1 <h2 and h4 <h3. In this example, the height change is linear. The drill 12 equipped with such a cutting edge tip 1 is shown in FIGS.
As shown in, by the action of the rake angle and the height change of the rising wall 8, both the outer peripheral blade 13 and the central blade 17,
In addition to exhibiting excellent sharpness, the chip 14 receives a deforming force that tends to extend in a direction parallel to the rotation axis of the drill 12.

The shape of the breaker groove 6 as described above is suitable for drilling cast iron which does not require special measures for chip disposal because the chips are subdivided by themselves, and the cutting resistance can be kept low. Further, since it is possible to prevent rubbing with the chip discharge groove 15, it is also suitable for drilling a high hardness material which tends to increase cutting resistance and an aluminum alloy which tends to cause adhesion. Less wear on the drill body.

[0018]

The cutting edge tip of the present invention is a cutting edge tip in which the same cutting edge tip can be used as both the outer peripheral blade and the center blade, and the breaker groove rises at both the outer peripheral blade and the center blade. Wall height changes can be aligned in the same direction. Therefore, if the height of the rising wall of the breaker groove is gradually lowered from the outer peripheral corner toward the rotation axis,
The chips are guided toward the wall surface of the chip discharge groove and collide,
As it is subject to forced deformation, chip breaking tends to occur without being affected by changes in cutting conditions, and as a result,
Expands the range of good chip disposal. A positive rake angle has the effect of improving chip sharpness and assisting chip deformability.

On the other hand, if the height of the rising wall of the breaker groove is gradually increased from the outer peripheral corner toward the rotation axis, the chips are sent out in the direction of the chip discharge groove in an attempt to extend in the direction parallel to the rotation axis. Therefore, for work materials that do not need to break chips, or for work materials that are extremely difficult to break,
It has the effect of smoothly discharging chips.

[Brief description of drawings]

FIG. 1A is a front view of a throw-away tip of the present invention, and FIGS. 1B and 1C are side views along respective main ridges.

2A is a cross-sectional view taken along the line AA of FIG.
(B) is sectional drawing which followed the BB line.

3A is a cross-sectional view taken along the line CC of FIG.
(B) is sectional drawing which followed the DD line.

FIG. 4 is a chip generation state diagram when the outer peripheral blade of the drill equipped with the cutting blade tip of FIG. 1 is in front.

5 is a chip generation state diagram when the central blade of the drill equipped with the cutting blade tip of FIG. 1 is in front.

FIG. 6A is a front view of a throw-away tip according to another embodiment of the present invention, and FIGS. 6B and 6C are side views along respective main ridges.

7A is a sectional view taken along the line AA of FIG.
(B) is sectional drawing which followed the BB line.

8A is a sectional view taken along the line CC of FIG.
(B) is sectional drawing which followed the DD line.

9 is a chip generation state diagram when the outer peripheral blade of the drill equipped with the cutting blade tip of FIG. 6 is in front.

FIG. 10 is a chip generation state diagram when the central blade of the drill having the cutting blade tip of FIG.

FIG. 11 is a front view showing an example of a conventional cutting blade tip.

12 (a) is a cross-sectional view taken along the line AA of FIG.
(B) is sectional drawing which followed the BB line.

FIG. 13 shows the tip of a throw-away drill,
(A) is a figure when the central blade is the front, (b) is a figure when the outer peripheral blade is the front.

[Explanation of symbols]

1 cutting edge tip 3 cutting edges 6 breaker grooves 8 rising wall 9 short side 10 long side 15 Chip discharge groove 16 walls 18 lands

Claims (2)

[Claims] 1. A cutting edge tip for a throw-away drill, which has a substantially parallelogrammatic flat plate shape and is provided with a breaker groove along the cutting edge on the upper surface, from a cutting edge of a rising wall of the breaker groove. Is formed so that the heights of the two are gradually higher and the other is gradually lower with increasing distance from the corners in two directions sandwiching an acute corner. Blade tip. 2. The cutting edge tip for a throw-away drill according to claim 1, wherein a rake face of the cutting edge tip is formed into a regular angle by the breaker groove or the narrow land.