WO2015194408A1

WO2015194408A1 - Drill

Info

Publication number: WO2015194408A1
Application number: PCT/JP2015/066435
Authority: WO
Inventors: 和昌栗塚
Original assignee: 住友電工ハードメタル株式会社
Priority date: 2014-06-17
Filing date: 2015-06-08
Publication date: 2015-12-23
Also published as: CN105473262A; JP6288585B2; CN105473262B; JP2016002617A; DE112015002883T5

Abstract

A drill: which has a thinning section formed at the center of rotation, and a cutting edge comprising a thinning section cutting edge formed in the thinning section and a concave arc cutting edge section that extends from the outer end of the thinning section cutting edge; and in which a honing surface or negative land is formed on the entire cutting edge. The width of the honing surface or negative land in the drill axis direction when viewed perpendicular to the drill axis gradually increases from the center of rotation to the outer end of the thinning section cutting edge, gradually decreases from the outer end of the thinning section cutting edge to a midpoint of the concave arc cutting edge section, and gradually increases from the midpoint to the outer end of the cutting edge.

Description

Drill

This invention relates to a drill in which the cutting edge is reinforced, and more particularly to a drill in which the cutting load is reduced while maintaining the strength of the cutting edge.

The strengthening process of the cutting edge of a scissors drill is usually performed by a method of blunting the cutting edge. The blunting of the cutting edge is performed by a method as shown in

Patent Documents

1 and 2 below, for example.

The drill of patent document 1 forms the negative land which blunts a blade edge on a rake face, and makes the width of the negative land attached to the thinning part cutting edge in the front view of the drill larger than the width of the negative land attached to the main cutting edge. .

ドリル Moreover, the drill of patent document 2 gives the honing process which rounds a blade edge to a blade edge part. The honing width of the thinning part cutting edge is made constant over the entire length of the thinning part cutting edge, and the honing width of the outer peripheral part cutting edge connected to the radial outer end of the thinning part cutting blade is cut at the radial outer end. Widened to more than 1.5 times the honing width of the blade.

JP 2009-18360 A JP 2004-268230 A

Conventionally, as a strengthening process of the cutting edge, the width of the negative land or the honing is made constant for the thinned portion cutting edge, the width is made constant for the outer peripheral portion cutting edge, or the width from the rotation center side to the outer peripheral side is changed. Processing to increase the width was adopted. However, in such a strengthening process, the cutting edge is unnecessarily blunted to a portion where it is difficult to apply a cutting load, which increases the cutting load.

An increase in cutting load reduces machining stability and adversely affects the drill life.

Therefore, the present invention has an object to reduce the cutting load while maintaining the strength of the cutting edge of the drill with the drill subjected to the strengthening process (blunting process) applied to the cutting edge as the object of improvement.

In order to solve the above problems, in the present invention, a thinning portion formed at the center of rotation, a thinning portion cutting edge formed at the thinning portion, and a concave arc cutting edge portion connected to an outer end of the thinning portion cutting edge A drill having a honing surface or a negative land formed in the entire region of the cutting edge, and the width of the honing surface or the negative land in the drill axis direction when viewed perpendicularly to the drill axis is the center of rotation. Gradually increasing from the outer end of the thinning portion cutting edge toward the intermediate point of the concave arc cutting edge portion, and gradually decreasing from the intermediate point to the outside of the cutting edge. The drill gradually increased toward the end.

ドリル In the drill of the present invention, the honing surface for reinforcing the cutting edge and the negative land are configured as described above, and the cutting load is reduced as compared with the conventional drill subjected to the cutting edge strengthening treatment.

It is a side view which shows an example of the drill of this invention. FIG. 2 is an enlarged view of a part of a side surface of the drill, which is a view perpendicular to the drill axis of the drill of FIG. 1. It is a figure which expands and shows the front of the drill of FIG. FIG. 4 is an enlarged cross-sectional view of a position along line XX in FIG. 3. It is an expanded sectional view showing other examples of blade edge processing of a drill of this invention. It is the figure which compared the measured value of the axial direction cutting load in a performance evaluation test.

Hereinafter, an embodiment of a drill according to the present invention will be described with reference to FIGS. 1 to 5 of the accompanying drawings. The illustrated drill 1 is a twist drill having a twisted groove 3 on the outer periphery of a main body 2.

The groove surface at the tip of the twisted groove 3 is a rake surface 4, and the groove surface of the thinning portion 7 formed at the ridge line at the position where the rake surface 4 intersects the flank 5 at the tip and the center of the tip of the main body 2. A cutting edge 6 is formed by a ridgeline at a position where the flank 5 intersects.

The scissors drill has a margin 8 and a shank 9 connected to the rear of the main body 2.

As shown in FIG. 3, the scissors cutting blade 6 includes a thinning portion cutting edge 6a along the thinning portion and an outer peripheral portion cutting blade 6b connected to the radially outer end of the thinning portion cutting edge 6a.

The illustrated outer peripheral cutting edge 6b includes a concave arc cutting edge 6b- ₁ connected to the outer end of the thinning cutting edge 6a, and a convex arc cutting extending from the outer end of the concave arc cutting edge 6b- ₁ to the outermost periphery. The blade portion 6b- ₂ is combined.

In addition, here, what is dented in the direction opposite to the rotation direction on the basis of the rotation direction of the drill is referred to as a concave arc cutting edge portion, and what is swollen so as to be convex in the rotation direction is referred to as a convex arc cutting edge portion. .

The blade cutting edge 6 is subjected to a cutting edge strengthening process over the entire area. In the exemplified drill edge strengthening process, the edge is rounded by a honing process. 2 and FIG. 3 is a honing surface formed by the edge-strengthening process.

On the honing surface 10, the width w in the drill axis direction when viewed perpendicularly to the drill axis (FIG. 2) gradually increases from the center of rotation toward the outer end of the thinning portion cutting edge 6 a.

Further, as it goes from the outer end of the thinning part cutting edge 6a to the maximum recessed middle point Mp of the concave arc cutting edge part 6b- ₁ , the drill axis direction width w as viewed perpendicularly to the drill axis gradually decreases. The width in the drill axis direction when viewed perpendicular to the drill axis gradually increases again from Mp toward the outer end of the cutting edge 6 (the radial outer end of the convex arc cutting edge portion 6b- ₂ ).

The appropriate width w of the honing surface 10 in the drill axis direction when viewed perpendicularly to the drill axis is 0.02 mm to 0.06 mm. By making the width 0.02 mm or more, the reinforcing effect of the cutting edge can be obtained without shortage.

In addition, by making the width 0.06 mm or less, it is not necessary to sacrifice the effect of reducing the cutting load.

If the radius of curvature of the concave arc cutting edge portion 6b- ₁ is set appropriately, for example, 0.5D (D is a drill diameter) or more, the concave arc cutting edge portion 6b- ₁ is intermediate between the concave arc cutting edge portion 6b- ₁ . The concentration of the cutting load applied to the point Mp hardly occurs, and the cutting load applied to the intermediate point Mp is smaller than the cutting load applied to the outer end of the thinning portion cutting edge 6a.

Therefore, the degree of strengthening of the cutting edge near the intermediate point Mp of the concave arc cutting edge portion 6b- ₁ (which is determined by the drill axis direction width w of the honing surface 10 when viewed perpendicularly to the drill axis) is determined by the thinning portion cutting edge 6a. It is possible to reduce the cutting load by suppressing the blunting more than necessary to the region where the cutting load is difficult to be applied.

Note that the honing surface 10 can be replaced with a negative land 11 as shown in FIG. Even with a structure in which the negative land 11 is provided on the rake face by polishing or grinding, the cutting edge can be strengthened.

This form also increases the width w in the drill axis direction in the negative view of the drill axis of the negative land gradually from the rotation center toward the outer end of the thinning portion cutting edge, and then the concave arc cutting edge portion from the outer end of the thinning portion cutting edge. By gradually decreasing toward the intermediate point, and gradually increasing again from the intermediate point toward the outer edge of the cutting edge, it is possible to prevent the cutting edge from being blunted more than necessary. Cutting load can be reduced.

The outer peripheral cutting edge 6b of the illustrated drill has a convex arc cutting edge 6b- ₂ on the outer end side. The outer peripheral cutting edge 6b has a concave arc cutting as shown in FIG. 2 of the above-mentioned patent document 2 from the inner end connected to the outer end of the thinning cutting edge 6a to the outer end extending to the outer periphery of the drill. You may be comprised with the blade.

A prototype of a carbide twist drill (sample 1) having a two-blade diameter D = φ8 mm provided with the blade shape shown in FIG. In Sample 1, a honing surface for reinforcing the cutting edge was formed over the entire area of the cutting edge.

On the honing surface, the width in the drill axis direction when viewed perpendicularly to the drill axis is gradually increased from the inner end to the outer end of the thinning portion cutting edge, and then the concave arc cutting edge portion of the thinning portion cutting edge is increased. It gradually decreased toward the intermediate point, and further increased gradually from the intermediate point of the concave arc cutting edge part toward the outermost end of the cutting edge.

The drill axial width of the honing surface at the inner end of the thinning part cutting edge in a perpendicular view of the drill axis is 0.02 mm, the drilling axial width of the honing surface at the outer end of the thinning part cutting edge is 0.05 mm, and a concave arc The drill axial width of the honing surface at the midpoint of the cutting edge is 0.02 mm, and the drill axial width of the honing surface at the outermost end of the cutting edge is 0.06 mm.

For comparison, a carbide twist drill (sample 2 and sample 3) having the same diameter and the same blade shape was also prototyped. In Sample 2, the width in the drill axis direction of the honing surface as viewed from the right angle of the drill axis was uniformly 0.06 mm over the entire cutting edge.

Sample 3 has a honing surface with a drill axis width of 0.02 mm at the rotation center in a right angle view of the drill axis and a honing surface with a drill axis width of 0.06 mm at the outermost edge of the cutting edge. The axial width was gradually increased from the center of rotation to the outermost edge of the cutting edge.

Using these Samples 1 to 3, drilling of 2 holes was carried out under the following conditions, and the cutting load at that time was measured.

-Cutting conditions-
Work material: SUS304
Cutting speed (peripheral speed) Vc = 60 m / min
Feed amount f = 0.15mm / rev

The cutting load is measured by a method of measuring the axial load applied to the measuring tool by placing the work material on the measuring tool (cutting dynamometer made by Nihon Kissler) and cutting the work material from above. It was.

The result is shown in FIG. As can be seen from FIG. 6, the cutting load of sample 1 is about 300 kgf · cm less than that of sample 2.
The fluctuation width of the cutting load is about 300 Kgf · cm in the sample 2, while the sample 1 is as small as 200 Kgf · cm.

Sample 3 has a peak cutting load peak value of about 1500 Kgf · cm at the beginning of cutting, whereas Sample 1 is stable with an upper limit of cutting load from the beginning of cutting to the end of machining of about 1200 Kgf · cm. Therefore, the fluctuation width of the cutting load during processing is also smaller than that of the sample 3.

結果 From the results of this evaluation test, the effectiveness of changing the width in the drill axis direction of the honing surface provided for the purpose of strengthening the cutting edge or the negative land when viewed perpendicularly to the drill axis can be seen.

DESCRIPTION OF SYMBOLS 1 Drill 2 Body part 3 Torsion groove 4 Rake face 5 Flank face 6 Cutting edge 6a Thinning part cutting edge 6b Outer peripheral part cutting edge 6b _-1 Concave arc cutting edge part 6b _-2 Convex arc cutting edge part 7 Thinning part 8 Margin 9 Shank 10 Honing surface 11 Negative land

Claims

A cutting edge including a thinning portion formed at the center of rotation, a thinning portion cutting edge formed in the thinning portion, and a concave arc cutting edge portion connected to an outer end of the thinning portion cutting edge, and the cutting edge A drill in which a honing surface or a negative land is formed in the entire area of
The width of the honing surface or the negative land in the drill axis direction when viewed perpendicularly to the drill axis gradually increases from the center of rotation toward the outer end of the thinning part cutting edge, and the concave arc cutting edge extends from the outer end of the thinning part cutting edge. A drill that gradually decreases toward an intermediate point of the section and gradually increases from the intermediate point toward the outer end of the cutting edge.
The drill according to claim 1, wherein a width in the drill axis direction of the honing surface or the negative land in a perpendicular view of the drill axis is 0.02 mm to 0.06 mm.
The drill according to claim 1 or 2, wherein a radius of curvature of the concave arc cutting edge is set to 0.5 times or more of a drill diameter.