JP2001239412A - Tip for throw-away type drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tip for a drill for simultaneously satisfying chip disposal of a central edge and an outer peripheral edge even for tough material easily discharging thick chips. SOLUTION: The tip 1 for the throw-away type drill is in a positive type in a substantially parallelogram flat plate shape, and a breaker groove 6 in the tip 1 for the throw-away type drill is formed more deeply and widely in the outer peripheral edge 2B than the central edge 2A. A negative shaped land 5 is provided adjacently between the outer peripheral edge 2B and the breaker groove 6, and the central edge 2A is not provided with a land 5 and is connected directly to the breaker groove.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tip for a throw-away type drill (hereinafter referred to as "drill tip") having a center blade and an outer peripheral blade and capable of using four corners. Provided is a drill tip that can provide good chip control even with easy-to-use materials.

[0002]

2. Description of the Related Art Conventionally, as a drill tip of this kind, there is one disclosed in, for example, Japanese Patent Application Laid-Open No. 6-91416. This drill tip has a so-called all-round breaker shape in which a breaker is formed substantially parallel to the cutting edge, and can be used also as a center blade and an outer peripheral blade of a throw-away type drill. On each side ridge of the diamond-shaped surface to be the rake face of the drill tip, a pair of side ridge cutting edges are formed adjacent to the acute-angled tops of the diamond-shaped surface, respectively. A pair of corner cutting edges shorter than the edge cutting edge are formed symmetrically with respect to the bisector of the top and at an intersection angle larger than the apex angle of the top in a V-shape. Has formed. The breaker is
Both the inner peripheral cutting edge and the outer peripheral cutting edge have the same width.

[0003]

Here, the problems of the prior art will be described below. The prior art described above is a drill tip that can be used as both the center blade and the outer peripheral blade, but since the breaker configuration of the center blade and the outer peripheral blade is the same,
In some cases, a problem occurs in chip control and smooth drilling cannot be performed. With the peripheral blade, the chips grow easily, and a deeply engraved breaker is required to curl the chips, but with the center blade, the chips naturally curl and there is no problem with chip processing. Breakers are not necessary because they are few, but rather
Breakers are needed to reduce cutting forces. In the case where a breaker having a deep engraving similar to that of the outer peripheral blade is formed in the center blade, chips may be clogged in the breaker, which may cause inconvenience. Therefore, since the role of the breaker differs between the outer peripheral blade and the center blade, it is not appropriate to configure a breaker having the same shape.

[0004] However, in the case of a drill tip having a negative land formed on the entire periphery of the cutting edge, the shear angle of the chip at the center edge becomes small, and the thick chip tends to be discharged. Thick chips are difficult to curl and can cause chip clogging. In particular, such a problem is likely to occur when processing a durable material such as mild steel or stainless steel. Such a problem becomes more remarkable as the feed rate is increased, and is an obstacle to performing high-efficiency machining.

Accordingly, an object of the present invention is to provide a drill tip that simultaneously satisfies chip control of a center blade and an outer peripheral blade even for a sticky material that easily discharges thick chips. is there.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a center edge forming a central portion of a bottom edge and an outer edge forming an outer peripheral portion of the bottom edge at a drill tip. As a blade, it is detachably mounted on the inner and outer peripheral sides of the throw-away type drill, and the cutting edge height is formed to be the same over the entire circumference, and between the cutting edge and the boss surface. Is a throw-away drill tip in which a concavely curved breaker groove is formed, wherein the throw-away drill tip is a generally parallelogram-plate-shaped positive-type throw-away drill tip; The groove is formed deeper on the outer peripheral blade than the center blade, and is formed to have a wide width, and a negative land is provided between the outer peripheral blade and the breaker groove. Land is characterized in that it does not Sonawara.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a state in which a drill tip 1 according to the present invention is incorporated in a drill body 12. The drill tip 1 according to the present invention is fixed to the drill body 12 by screws 14 through a central mounting hole 13. This drill tip 1 is a positive type drill tip 1 having a substantially parallelogram flat plate shape, and a cutting edge is formed at the intersection ridge portion of the rake face 3 and the flank face 4. The cutting edge is the outer edge 2A and the center edge 2
This is also used as B. The cutting edge height is the same over the entire circumference. In other words, the center drop amount is the same for the outer peripheral blade 2A and the center blade 2B.

As shown in FIGS. 3 and 4, on the upper surface of the drill tip 1, a central mounting hole 13, a concavely curved breaker groove 6, and a land 5 provided adjacent to the outer peripheral blade 2A are formed. . Further, a flat surface 10 and a rising inclined surface 11 are formed behind the breaker groove 6 of the center blade 2B.
The center mounting hole 13 is for mounting the drill tip 1 to the drill body 12 as described above. The breaker groove 6 mainly curls the chip C to form the chip C.
It is intended for smooth discharge of gas and is a full-circle breaker. The width of the breaker groove 6 is such that the breaker width Wa of the outer peripheral blade 2A is larger than the breaker width Wb of the center blade 2B, and the depth of the breaker groove 6 is that the breaker depth Da of the outer peripheral blade 2A is equal to that of the center blade 2B. It is carved deeper than the breaker depth Db.

As described above, the outer peripheral blade 2A and the central blade 2B
The reason why the breaker configuration is different between the two is that the roles played by the two in the chip processing are different. Outer edge 2A
In this case, the problem is to avoid the entanglement of the chip C by curling the chip C, and therefore, the breaker width Wa and the breaker depth Da are sufficiently ensured. On the other hand, in the center blade 2B, it is an issue to avoid chip clogging and to suppress a sharp increase in cutting resistance. For this purpose, a flat surface 10 and a rising inclined surface 11 that follow the breaker groove 6 are formed, and the breaker depth is reduced. Db is reduced.

Next, as shown in FIG. 4A, the land 5 is formed in a negative shape. The reason for the negative shape is to increase the cutting edge strength. FIG.
(B) shows the cutting edge cross section of the center blade 2B,
The land 5 is not formed on the center blade 2B, and is directly connected to the breaker groove 6 having a positive rake angle α. This is because, when the negative land 5 is formed over the entire circumference of the cutting edge, the shear angle of the chip C of the center blade 2B becomes small, and the thick chip tends to be discharged. . In particular, such a problem is likely to occur when processing a durable material such as mild steel or stainless steel. Preferably, the rake angle α is more than 0 ° and not more than 20 °. The rake angle α is set to be larger than 0 ° in order to allow the thin chips C to be discharged and to curl the chips C. The rake angle α is set to 20 ° or less in order to prevent a decrease in fracture resistance.

FIG. 5 is a diagram showing a chip C with or without the land 5.
FIG. 5 is a diagram for explaining a change in thickness. In FIG. 5A having lands 5, thick chips C are generated, and in FIG. 5B without lands 5, thin chips C are generated. Even when a positive land 5 is formed on the center blade 2B,
It has been confirmed that thin chips C are generated and effective in preventing chip clogging.

On the rake face 3 of the drill tip 1, a plurality of concave grooves 9 and a plurality of ridges 8 for reducing contact friction are provided.
Is provided. Each of the concave groove 9 and the ridge 8 has an effect of reducing the contact area of the rake face with the chip C, and suppressing an increase in cutting resistance and an increase in cutting heat. The concave groove 9 is formed in the breaker groove 6 for guiding the chip C shaved by the center blade 2B, starts behind the cutting edge, extends in a direction away from the cutting edge, and is near the inner edge of the breaker groove 6. Ends with In order to enhance the above-described effects, it is preferable to arrange the concave grooves 9 in the chip outflow direction. In the present embodiment, a plurality of the grooves 9 are arranged substantially perpendicular to the center blade 2B. The ridge 8 is formed in the breaker groove 6 for guiding the chip C shaved by the outer peripheral edge 2A, starts behind the cutting edge, extends in a direction away from the cutting edge, and extends along the inner edge of the breaker groove 6. It ends near.

According to the present invention, chips can be curled continuously by the outer peripheral blade, and chips can be smoothly discharged by the central blade without discharging thick chips. In particular, it is effective for sticky materials such as mild steel and stainless steel.

[Brief description of the drawings]

FIG. 1 shows an example of a throw-away type drill, (a)
Is a front view, and (b) is a bottom view.

FIG. 2 shows the tip of the indexable drill of FIG. 1,
(A) is a front view, (b) is a rear view.

FIG. 3 is a plan view of a drill tip showing an example of an embodiment of the present invention.

4A is a sectional view taken along line AA of the drill tip shown in FIG. 3, and FIG. 4B is a sectional view taken along line BB.

FIGS. 5A and 5B are explanatory diagrams showing a chip generation state when there is a land, and FIG. 5B is an explanatory diagram showing a case where there is no land.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drill tip 2A Outer edge 2B Center edge 5 Land 6 Breaker groove 10 Flat surface 11 Ascending surface 12 Drill body Da Breaker depth of outer edge Db Breaker depth of center edge

Claims (3)

[Claims] 1. A detachable attachment is provided at the tip of a drill as a center blade constituting a central portion of a bottom blade and an outer peripheral blade constituting an outer peripheral portion of the bottom blade on an inner peripheral side and an outer peripheral side of a throw-away type drill. In addition, in a throw-away type drill insert, the cutting edge height is formed to be the same over the entire circumference, and a concave curved shape breaker groove is formed between the cutting edge and the boss surface. The tip for a throw-away drill is a generally parallelogram-plate-shaped, positive-type tip for a throw-away drill, and the breaker groove is formed deeper at the outer peripheral edge than at the central edge, and is formed to have a wide width. Further, a negative land is provided between the outer peripheral blade and the breaker groove, while the land is not provided on the center blade. H. 2. The indexable drill according to claim 1, wherein the breaker groove provided adjacent to the center blade has a positive rake angle of more than 0 ° and not more than 20 °. Chips. 3. A releasably attached to the inner and outer peripheral sides of a throw-away drill as a central blade forming a central part of a bottom blade and an outer peripheral blade forming an outer peripheral part of the bottom blade at a tip end of the drill. In addition, in a throw-away type drill insert, the cutting edge height is formed to be the same over the entire circumference, and a concave curved shape breaker groove is formed between the cutting edge and the boss surface. The tip for a throw-away drill is a generally parallelogram-plate-shaped, positive-type tip for a throw-away drill, and the breaker groove is formed deeper at the outer peripheral edge than at the central edge, and is formed to have a wide width. Further, a negative land is provided between the outer peripheral blade and the breaker groove, while a positive land is provided between the center blade and the breaker groove. Characteristic indexable drill tip.