JP2000288815A - Throw-away type drill and cutting edge tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an appropriate breaker width to a cutting edge tip on even a small diameter drill. SOLUTION: A clearance angle is applied on an outside face 3 of a cutting edge tip 1 shaped in a roughly triangular flat plate in a direction to a bottom from an upper face 4 and a cutting edge 6 of the upper face 4 is formed so that it's practically center point P is at a higher level and it gradually inclines toward corners to a lower level. The cutting edge tip 1 is fixed by screwing from a tip face side of a drill main body 11. The outside face 3 of the cutting edge tip 1 becomes a cutting face and a broad breaker 8 suited for chip control can be provided even on a small cutting edge tip.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting edge having a new shape and a throw-away type drill having the cutting edge.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show examples of a conventional throw-away type drill, in which the same parts as those of an embodiment of the present invention described later are denoted by the same reference numerals. In this drill, a tip seat 13 is dug at the tip of a pair of chip discharge grooves 12 provided at one end of the drill body 11 along the axis from the surface side of the groove. This tip seat 1
3, the cutting edge tip 1 is detachably mounted by the tightening screw 14.

The cutting edge chip 1 has a substantially triangular flat plate shape, and a substantially midpoint P of the cutting edge 6 projects outward to form a hexagonal shape. A mounting hole 2 is drilled in the center, and the center point P is arranged so as to be the forefront, and is fixed to the drill body 11 with screws. Normally, a main cutting edge of a drill is formed by combining two cutting edge tips 1 serving as an outer peripheral edge and a center edge, respectively. A groove-shaped breaker 8 is provided along the cutting edge 6 to improve cutting performance.

[0004]

For a throw-away drill, chip control is a major factor that determines the cutting performance of the drill. The shape of the breaker provided to improve chip disposal is required to be appropriate for the rake angle, breaker width, etc.The problem here is with regard to the breaker width of the cutting tip in small diameter drill-away type drills. is there.

[0005] In the case of a throw-away type drill, it is necessary to reduce the cutting tip in correspondence with the reduction in the drill diameter. However, just because of the small diameter,
Since the cutting conditions are not reduced proportionally, the breakers cannot be reduced similarly. The similarly narrowed breaker width is too narrow, causing chip clogging,
The cutting performance is reduced by increasing the cutting resistance.

[0006] By the way, a throw-away type drill as in the conventional example described above does not have enough space for setting an appropriate breaker width when the cutting edge tip becomes small. In order to maintain the strength and durability of the tightening screw, the mounting hole cannot be made too small, and the setting space for the breaker width is further restricted.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a chip discharge groove extends along an axis at one end of a round bar-shaped drill body. In a throw-away type drill in which a cutting edge tip is detachably mounted on a tip end surface of a drill body provided, the cutting edge tip presents a substantially triangular flat plate, and the outer surface thereof has a top surface to a bottom surface direction. The relief angle is given to each side edge of the outer edge of the upper surface serving as a cutting edge, is formed so that the approximate middle point is at a high position, and has a slope gradually lower toward the corner, the said The drill body is configured such that one side surface of the cutting edge tip is a rake face, and at least two of the cutting edge tips are used to create a cutting edge connected from the center to the outer periphery in the rotation trajectory. And

[0008] Further, a breaker is provided on an outer surface of the cutting blade tip along the cutting blade, and is formed so as to act as a rake face with a breaker. The corner on the upper surface of the tip is provided with a chamfer in an arc shape or a chamfer shape in a rake view with respect to a corner arranged on the outer peripheral side when mounted on the drill body, and the direction of the attachment is , In a direction perpendicular or acute to the cutting edge when viewed from above.

According to the present invention, a main cutting edge can be created by combining the same cutting edge tip, and a small diameter drill, specifically, a high performance indexable drill having a diameter of about 26 mm or less is realized. Is possible. The cutting edge tip has a so-called vertical tip configuration, which is attached from the tip end face side of the drill body, but has a positive tip shape having a tip angle necessary for being formed as a drill. Since the mounting hole is formed from a different direction from the rake face, the thickness of the flat tip can be changed regardless of the size of the cutting tip. Then, by setting the thickened side surface as a rake surface, an appropriate breaker width can be freely set.

[0010] Even a so-called vertical cutting blade tip can be formed into a shape in which a corner is chamfered to strengthen the cutting edge. The direction in which the chamfer is provided is limited so that the outer periphery of the chamfer can be secured.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 to 3 show a throw-away type drill of the present invention, and FIG. 4 shows a cutting edge tip thereof.

In FIG. 4, the cutting edge chip 1 has a substantially triangular plate shape, a mounting hole 2 is formed in the center thereof, and a clearance angle is provided on the outer side surface 3 from the upper surface 4 to the bottom surface 5. In addition, it is a positive chip with a so-called mounting hole. Each side ridge at the outer edge of the upper surface 4 is a cutting edge 6, and each cutting edge 6 is formed in a triangular mountain shape having a slope whose middle point P is higher and gradually lowers toward the corner 7. You.

The cutting edge tip 1 is used as a so-called vertical tip in which the outer surface 3 is a rake face. The outer side surface 3 is provided with a breaker 8 along the cutting edge 1 for performing chip processing. The breaker 8 is formed by providing a groove-like recess on the outer side surface 3 or providing a stepped surface 9 projecting as in this embodiment. According to this configuration, even if the cutting edge chip 1 is small, a space enough to make the width of the breaker 8 appropriate can be secured by changing the chip thickness.

The corner 7 on the upper surface 4 of the cutting tip 1 has a corner, which is disposed on the outer peripheral side when mounted on a drill body to be described later, as viewed from the outside surface 3, that is, the rake surface in FIG. An arc-shaped or chamfer-shaped chamfer 10 as shown in b) is provided. The direction of the attachment is such that the angle α formed with the cutting edge 6 when viewed from above the upper surface 4 is a right angle or an acute angle.

1 to 3, a drill body 11 is shown.
Has a round bar shape, and a pair of chip discharge grooves 12 extends at one end thereof along the axis. The chip discharge groove 12 is formed as a straight groove or a twist groove. The tip seat 1 is provided on the tip end surface of the drill body 11 on the side where the chip discharge groove 12 is provided.
3 is recessed. The cutting edge tip 1 is placed on the tip seat 13 and is removably fastened and fixed to the drill body 11 by a fastening screw 14 inserted into the mounting hole 2.

The tip seats 13 are displaced in the diametrical direction, and the two cutting edge tips 1 mounted thereon serve as an outer peripheral edge and a central edge, respectively. In the rotation trajectory, the outer cutting edge and the inner cutting edge form a main cutting edge connected from the axis to the outer circumference. The midpoint P is at the forefront of the drill, and a cutting edge 6 having a tip angle is formed. The outer surface 3 of the cutting tip 1 is a rake face provided with a breaker 8 having an appropriate width. The corner 7 is provided with a chamfer 10 to enhance the strength of the corner.

An oil hole 15 penetrates the drill body 11 and is open at the tip. Cutting fluid supplied from the inside promotes cooling of cutting heat and chip discharge.

The indexable drill and the cutting edge tip of the present invention are configured so that an appropriate breaker width can be provided even with a small cutting edge tip in a small diameter drill. In spite of the configuration of the vertical insert, since it is a positive insert and the corners are strengthened, a small-diameter throw-away drill with small thrust and excellent chip discharge performance can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of an entire drill according to an embodiment of the present invention.

FIG. 2 is a side view of a drill tip.

FIG. 3 is an enlarged view of a tip portion of the drill in FIG. 1;

4A and 4B show a cutting edge tip according to an embodiment of the present invention, wherein FIG. 4A is a front view, FIG. 4B is a side view, and FIG. 4C is a cross-sectional view passing through a point P in FIG. .

FIG. 5 is a front view showing an example of a conventional indexable drill.

FIG. 6 is a side view of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cutting blade tip 3 Outer side surface 4 Top surface 7 Corner 6 Cutting blade 8 Breaker 10 Chamfer 13 Tip seat

Claims (4)

[Claims] 1. A chip discharge groove extends along an axis at one end of a drill body having a round bar shape, and a cutting tip is detachably attached to a tip end surface of the drill body provided with the chip discharge groove. In the throw-away type drill that is mounted, the cutting edge tip presents a substantially triangular flat plate, and the outer surface thereof is provided with a clearance angle from the upper surface toward the bottom surface, and each side edge of the upper surface outer edge serving as the cutting blade is: The drill body is formed so that its substantially middle point is at a high position and has a slope that becomes gradually lower toward the corner, and the drill body has a rake face on one side surface of the cutting edge tip, and at least two cutting edge tips are provided. A throw-away drill, wherein a cutting edge is formed so as to connect from the center to the outer periphery in the rotation trajectory. 2. The cutting edge chip has a substantially triangular flat plate, and a clearance angle is provided on the outer surface from the upper surface toward the bottom surface, and each side edge of the outer edge of the upper surface serving as a cutting edge has a substantially midpoint. The cutting tip according to claim 1, wherein the cutting tip is mounted to have a slope that is higher and gradually becomes lower toward the corner. 3. The cutting edge tip according to claim 2, wherein a breaker is arranged on the outer surface of the cutting edge along the cutting edge so as to act as a rake face with a breaker. Cutting edge chip. 4. A corner on an upper surface of the cutting edge tip is provided with a chamfer which becomes an arc shape or a chamfer shape when viewed from a rake face with respect to a corner arranged on an outer peripheral side when mounted on the drill body. The cutting edge tip according to claim 2 or 3, wherein the direction of the attachment is at a right angle or an acute angle to the cutting edge in a top view.