JPS63229210A - Drill - Google Patents

Abstract

PURPOSE:To avoid the generation of excessive banishing force by providing the surfaces to be pressed facing to the outside of a radial direction and crossing a cutting edge arranging direction at right angles and in the axial direction end view of a drill on the external peripheral surface of a shank section. CONSTITUTION:When a drill 31 is inserted into a holder fitting hole, and the surfaces to be pressed which are provided to the drill 31 facing to the outside of a radial direction and crossing an arranging direction of a cutting edge 16 at right angles and in the axial direction end view of the drill is pressed and fixed, the drill 31 is off-centered in the arranging direction of the cutting edges 16. At this time, when the drill 31 is rotated, the external peripheral side end edge 16a of the cutting edges 16 on the position opposite to the side of this surface 32 to be pressed in the axial direction end view draws a rotational locus E having the largest revolving radius: cutting is performed by this external peripheral side end edges 16a. The first margin sections 19 just after the external peripheral side end edges 16a is, therefore, pressed to the internal peripheral surface of the hole being which is being drilled. As a result the generation of excessive banishing force can be avoided, and the increase in banishing torque can also be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drill provided with two linear chip discharge grooves and four margins on the outer periphery.

``Prior art'' Conventionally, as for the above-mentioned drill, the drills shown in Figs.
A drill It as shown in the figure is known. This drill 11 includes a tool body 12, and a blade portion 13 is provided at the front portion of the tool body 12. This blade part 13 is
It has a peeling tip 14 at the tip, and two chip discharge grooves 15, 15 are provided on the outer periphery at equal intervals in the circumferential direction. This chip discharge groove 15 is arranged in a straight line from the tip of the blade portion 13 toward the rear. The said chip discharge ii
A cutting edge 16 is provided at the tip of the surface facing the rotation direction of +T 15.
is provided, and the flank of this cutting blade 16 is filled with oil 61.
7 are provided. Land portion 1 on the outer periphery of the blade portion 13
8, the edge adjacent to the surface facing the rotational direction of the chip evacuation groove 15 has a first margin portion (marper 1%) extending rearward from the cutting edge 16 (1+07+4 chill l+ Muhap 11th - L Nana - Old 3 Moko 9nd Part 18
A second margin portion (margin portion) 20 is provided at an edge adjacent to a surface facing in a direction opposite to the rotational direction of the chip discharge 7f+715.

On the other hand, a shank portion 21 is provided at the rear of the tool body 12. The outer circumferential surface of the shank portion 21 has the cutting edge ' facing outward in the radial direction and viewed from the tip in the axial direction.
16. A suppressed surface 22 arranged parallel to 16 is provided.

As shown in FIG. 7, such a drill 11 is constructed by inserting its shank portion 21 into a fitting hole 24 of a holder 23 and pressing the suppressed surface 22 with a bolt 25.
It is fixed to the holder 23.

"Problems to be Solved by the Invention" By the way, a play is provided between the outer diameter of the shank portion 21 and the inner diameter of the fitting hole 24 to facilitate fitting. Therefore, the axis of the drill 11 is
By being pressed by the holder 23, the holder 23 is eccentrically centered by e with respect to the axis S of the holder 23.

Therefore, when this holder 23 is attached to the shaft and rotated, as shown in FIG.
Draw a rotation locus C whose radius is 0, which is the largest. Therefore, during drilling, the second margin portion 20 on the opposite side to the suppressed surface 22 is pressed against the inner circumferential surface of the drilled hole, which generates an excessive burnishing force and increases the burnishing torque. There was a problem in that the drill broke.

By the way, in hole drilling using a specialized machine such as a recent transfer machine, in order to facilitate quick change of the drill, the outer diameter of the holder 23 and the holder 23 are
There is also a fairly large play between the shaft and the inner diameter of the shaft to which it fits. Therefore, due to the synergistic effect of the play between the drill 11 and the holder 23 and the play between the holder 23 and the shaft, the final eccentricity m of the drill has recently reached about 0.4 mm. many.

For this reason, solving the above problems is of great importance.

"Means for Solving the Problems" The present invention has been made to solve the above problems, and includes a cutting edge on the outer peripheral surface of the shank portion, which faces outward in the radial direction and when viewed from the tip in the axial direction of the drill. The structure is such that a suppressed surface is provided orthogonal to the direction in which the suppressed surface is disposed.

"Function" This invention provides a suppressed surface on the outer circumferential surface of the shank portion that faces outward in the radial direction and is orthogonal to the cutting edge arrangement direction when viewed from the tip in the axial direction of the drill. When the drill is inserted into the matching hole and fixed by pressing the suppressed surface, the drill becomes eccentric in the direction in which the cutting blade is provided. Here, when this drill is rotated, the outer circumferential edge of the cutting edge located on the opposite side to the suppressed surface in the axial direction draws a rotation locus having the largest rotation radius, and the outer circumferential side of this cutting edge Cutting is performed by the edges. Therefore, it is possible to prevent the margin portion following the outer circumferential edge of the cutting blade from being pressed against the inner circumferential surface of the drilled hole and generate an excessive burnishing force, and also prevent burnishing torque from increasing. This prevents the drill from breaking.

"Embodiment" Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 4. In addition, in these figures, the same reference numerals are given to the parts having the same configuration as those of the conventional example, and the explanation thereof will be omitted.

1 and 2 are diagrams showing a drill 31 according to the present invention. In this drill 31, the shank portion 2
1 is provided with a suppressed surface 32 which faces radially outward and is disposed in a direction perpendicular to the cutting edge 16, 16 when viewed from the axial tip.

As shown in FIG. 3, such a drill 31 is constructed by inserting its shank portion 21 into the fitting hole 24 of the holder 23 and pressing the suppressed surface 32 with a bolt 25.
It is fixed to the holder 23.

Here, there is usually some play between the outer diameter of the shank portion 21 and the inner diameter of the fitting hole 24. Therefore, since the drill 3'°l is pressed by the bolt 25, it is eccentric by e with respect to the axis S of the holder 23, as shown in FIG.

By the way, in the drill 31, since the pressed surface 32 is provided in the direction perpendicular to the cutting edge 16, 16 when viewed from the axial tip (4), when the boulder 23 is rotated in the above-mentioned installed state, , as shown in FIG. 4, the outer peripheral edge 1 of the cutting blade 16 on the opposite side to the pressed surface 32 when viewed from the tip in the axial direction.
6a draws a rotation locus E with the largest radius. Therefore, during drilling, the surface outer circumference @ 16 a follows its rotational trajectory E
Because it is sent forward while cutting the work material in the area,
The biting property is stabilized, and the first margin portion 19 extending to the rear of the outer peripheral edge 16a can be prevented from being pressed against the inner peripheral surface of the perforation hole.

This makes it possible to prevent excessive burnishing force from being applied to the margin portion, reduce burnishing torque, and prevent breakage of the drill.

In addition, in the above embodiment, as a drill, the blade part 13
Although a drill with a tip 14 provided at the tip thereof is used, the present invention is not limited to this, and the entire drill may be made of a single material.

"Effects of the Invention" As explained above, according to the present invention, there is provided a suppressed surface on the outer circumferential surface of the shank portion, which faces radially outward and is orthogonal to the arrangement direction of the cutting blade when viewed from the tip in the axial direction of the drill. The provision of a The effect is that it can be prevented.

[Brief explanation of the drawing]

1 and 4 are views showing one embodiment of the present invention, in which FIG. 1 is a side view thereof, FIG. 2 is a view from the tip in the axial direction, and FIG. 3 is a diagram showing a drill attached to a holder. 4 is a sectional view showing the state, FIG. 4 is an axial tip end view showing the rotational locus of an eccentric drill, FIGS. 5 and 8 are views showing an example of a conventional drill, and FIG. 5 is a side view of the drill. 6 is a view as seen from the tip in the axial direction, FIG. 7 is a cross-sectional view showing the state in which the drill is attached to the holder, and FIG. 8 is a view as seen from the tip in the axial direction showing the rotation locus of the eccentric drill. 12... Tool body, 13... Blade part, i
5... Chip discharge groove, 16... Cutting blade, 1
8... Land part, 19... First margin part (margin part), 20... Second margin part (margin part), 21...・Shank part, 3
1...Drill, 32...Pressed surface.

Claims (1)

[Claims] A blade section is provided at the front part of the tool body, and a shank section is provided at the rear part, and the blade section is provided with two chip evacuation grooves extending linearly rearward from the tip thereof, and the rotation direction of the chip ejection grooves is A cutting edge is provided at the tip of the surface facing the cutting edge, and an edge portion of the land portion on the outer periphery of the blade adjacent to the surface facing the rotational direction of the chip evacuation groove, and an edge portion opposite to the rotational direction of the chip evacuation groove. In the drill, a margin portion is provided on each edge portion adjacent to the surface facing the direction, and the cutting edge is provided on the outer circumferential surface of the shank portion, facing radially outward and in the direction in which the cutting edge is disposed when viewed from the tip in the axial direction of the drill. A drill characterized by having a pressed surface perpendicular to the .