DE112015002883T5 - DRILL - Google Patents

Abstract

A drill comprises: a diluting part formed at a rotational center, and a cutting edge including a diluting part cutting edge formed on the diluting part and a recessed arcuate cutting part adjoining an outer end of the diluting part cutting edge, wherein a honing face or a negative chamfer is formed over the entire length of the cutting edge, and wherein the drill axis width of the honing surface or the negative chamfer gradually increases in a view perpendicular to the drill axis from the center of rotation to the outer end of the diluting section cutting gradually from the outer end of the thinner Thinner Teilschneide becomes smaller to a middle point of the recessed-arc-shaped cutting part and gradually becomes larger from the middle point to the outer end of the cutting edge.

Description

Technical area

The invention relates to a drill on which a reinforcing treatment is performed on a cutting edge, and more particularly to a drill on which the cutting load is reduced while maintaining the strength of the cutting edge.

State of the art

A cutting edge augmentation treatment of a drill is usually performed by a method of blunting the cutting edge. The blade is blunted, for example, by the method disclosed in the below-mentioned Patent Literatures PTL1 and PTL2.

In the drill of the PTL1, a negative land that blunts a blade is formed on an inclined surface, and the width of a negative land in the front view of the drill is made larger in a diluting part blade than the width of a negative land in the main cutting edge.

Furthermore, a honing treatment for rounding a cutting edge on a cutting part is performed on the drill of the PTL2. The honing width of a dilution part blade is made constant over the entire length of the dilution part blade. And, the honing width of a peripheral blade connected to the radially outer end of the diluting part blade is widened to 1.5 times or more the honing width of the diluting part blade at the radially outer edge.

References

patent literature

• PTL 1: Untested Japanese Patent Application Publication No. 2009-18360
• PTL 2: Untested Japanese Patent Application Publication No. 2004-268230

Summary of the invention

Technical problem

As a reinforcing treatment for a blade, a treatment is conventionally used in which for a thinning blade the width of a negative bevel or honing is constantly provided or in which for a peripheral blade the width of the peripheral blade is constantly provided or increased from the rotational center side to the peripheral side , However, in such a reinforcing treatment, the blade is blunted more than necessary at a part which is not likely to be cut. This increases the cutting load.

An increase in the cutting load reduces the stability of the processing and has a negative effect on the life of the drill.

The invention thus relates to an improvement on a drill on which a reinforcing treatment (blunting treatment) is performed on a cutting edge, an object of the invention being to reduce the cutting load while maintaining the strength of the cutting edge of the drill.

Troubleshooting

In order to solve the above-mentioned problem, the invention provides a drill comprising: a thinning part formed at a turning center; and a cutting edge comprising a diluting part cutting edge formed on the diluting part and a recessed arcuate cutting part adjoining an outer end of the diluting part cutting edge, wherein a honing face or a negative land is formed over the entire length of the cutting edge; and wherein the drill axis width of the honing face or the negative land gradually increases in a view perpendicular to the drill axis from the turning center to the outer end of the diluting die, gradually decreases from the outer end of the diluting die to a middle point of the recessed-arc shaped cutting part and gradually increases from the middle point to the outer end of the cutting edge.

Advantageous Effects of the Invention

On the drill according to this invention, a honing surface and a negative chamfer for reinforcing a blade are formed as described above, and a cutting load is reduced as compared with a drill on which a conventional blade reinforcing treatment is performed.

Brief description of the drawings

1 is a side view showing an example of a drill according to the invention.

2 is a view perpendicular to the drill axis of the drill of 1 and shows an enlarged view of a portion of the side of the drill.

3 is a view of the front of the drill from 1 on an enlarged scale.

4 FIG. 15 is an enlarged sectional view taken at a position along the line XX of FIG 3 ,

5 Fig. 10 is an enlarged sectional view showing another example of a drill cutting treatment according to the invention.

6 Figure 11 is a graph showing measured values of the axial cutting load in a performance evaluation test.

Description of embodiments

Hereinafter, an embodiment of a drill of this invention with reference to the accompanying drawings of 1 to 5 described. The drill 1 is a twist drill that has a spiral groove 3 on the outer circumference of a main body 2 having.

The groove surface at the tip end of the spiral groove 3 is an oblique surface 4 , where a cutting edge 6 through the ridge line at the position where the beveled surface 4 and a flank surface 5 at the tip end, and through the ridge line at the position where a groove surface of a dilution part 7 at the top center of the main body 2 and the flank surface 5 Cross each other is formed.

The drill has an edge 8th and a shaft 9 , the back of the main body 2 connects, on.

As in 3 shown, is the cutting edge 6 from a dilution cut edge 6a along the dilution part and a peripheral cutting edge 6b at the radially outer end of the dilution section cutting edge 6a followed.

The peripheral cutting edge 6b is a combination of a recessed-arched cutting part 6b-1 and a protruding-arc-shaped cutting part 6b-2 , wherein the recessed-arcuate cutting part 6b-1 with the outer end of the dilution part cutting edge 6a is connected and wherein the above-arc-shaped cutting part 6b-2 from the outer end of the recessed-arcuate cutting part 6b-1 extends to the outermost circumference.

With respect to the rotational direction of the drill, a blade recessed in the direction opposite to the rotational direction is referred to as a recessed-arc shaped blade part, and a blade protruding in the rotational direction is referred to as a protruding arcuate blade part.

At the cutting edge 6 For example, a reinforcing treatment is performed for the cutting edge over the entire extent thereof. In the reinforcing treatment for a cutting edge of the illustrated drill, the cutting edge is rounded by a honing treatment. The reference number 10 in 2 and 3 indicates the honing surface formed by the reinforcing treatment for the cutting edge.

At the honing area 10 increases the drill axis width w in the direction perpendicular to the drill axis view ( 2 ) gradually from the center of rotation to the outer end of the dilution section blade 6a ,

Furthermore, the honing surface 10 such that the drill axis width w in the view perpendicular to the drill axis gradually from the outer end of the dilution part of the cutting edge 6a to the most recessed center point Mp of the recessed arcuate section 6b-1 and that the drill axis width in the view perpendicular to the drill axis gradually returns from the middle point Mp to the outer end (the radially outer end of the protruding-arc-shaped cutting part) 6b-2 ) of the cutting edge 6 increased.

The drill axis width w of the honing surface 10 in the view perpendicular to the drill axis is preferably between 0.02 mm and 0.06 mm. The width of 0.02 mm or more allows a sufficient reinforcing effect for the blade to be obtained.

In addition, by a width of 0.06 mm or less, the effect of a reduced cutting load is not impaired.

When the radius of curvature of the recessed-arc-shaped cutting part 6b-1 is set correspondingly (for example, the radius of curvature is set to 0.5D (D is the drill diameter) or larger), it is unlikely that a concentration of the center point Mp of the recessed-arc shaped cutting part becomes 6b-1 applied cutting load occurs, and the cutting load applied to the middle point Mp becomes smaller than that on the outer end of the diluting part blade 6a applied cutting load.

Therefore, the (by the drill axis width w of the honing surface 10 in the view perpendicular to the drill axis) determines the degree of reinforcement of the cutting edge in the vicinity of the central point Mp of the recessed-arc-shaped cutting part 6b-1 less than the degree of reinforcement at the outer End of dilution section cutting edge 6a be. In addition, it is possible to prevent an area which is not likely to be subjected to a cutting load from being more than required to be blunted. And furthermore, the cutting load can be reduced.

It should be noted that the honing surface 10 through a negative chamfer 11 as in 5 can be replaced. The cutting edge can be reinforced by a structure in which the inclined surface by polishing and grinding with the negative chamfer 11 is provided.

With this configuration, the drill bit axis width w of the negative land in the drill axis perpendicular to the drill bit gradually increases from the rotation center to the outer end of the dilution part blade, then generally decreases from the outer end of the dilution part blade to the middle point of the recessed-arc shaped part and increases generally back from the middle part to the outer end of the cutting edge, thereby preventing a part of the cutting edge, which is not likely to be subjected to a cutting load, from being blunted more than necessary and thereby reducing the cutting load.

It should be noted that in the peripheral cutting edge 6b of the drill shown the above-arc-shaped cutting part 6b-2 is formed on the side of the outer end. The entire length of the peripheral cutting edge 6b from the inner end that abuts the outer end of the dilution part blade 6a connects to the outer end, which extends to the outer periphery of the drill, through the recessed-arc-shaped cutting part as in 2 formed PTL2 shown.

EXAMPLES

A superhard twist drill (sample 1) with a diameter D = φ8 mm and a two-piece cutting edge with the in 1 cutting mold shown was produced as a prototype. In the sample 1, a honing surface for reinforcing the cutting edge is formed over the entire length of the cutting edge.

In the honing surface, the drill axis width gradually increases in the drill perpendicular to the drill axis from the inner end to the outer end of the diluting part, then gradually decreases from the outer end of the diluting part cutting to the central part of the recessed-arc-shaped portion and is generally increased from the central point of the recessed-arcuate cutting part to the extreme end of the cutting edge.

The drill bit axis width of the honing face in the drill axis perpendicular to the inner end of the diluting die cutter was 0.02 mm, the drill axis width of the honing face at the outer end of the diluting die cutter was 0.05 mm, the drill bit axis width of the honing face at the middle part of the deepening arcuate edge portion was 0.02 mm, and the drill axis width of the honing face at the extreme end of the blade was 0.06 mm.

For comparison purposes, superhard twist drills (Sample 2, Sample 3) of the same diameter and cutter shape were also prototyped. In Sample 2, the drill axis width of the honing surface in the view perpendicular to the drill axis was uniformly 0.06 mm over the entire length of the cutting edge.

Further, in the sample 3, the drill axis width of the honing face at the center of rotation in the view perpendicular to the drill axis was 0.02 mm, the drill axis width of the honing face at the extremity of the cutting edge was 0.06 mm, and the drill axis width of the honing face gradually increased from that Turning center to the extreme end of the cutting edge.

Using Samples 1 to 3, drilling of each two holes was conducted under the following conditions, and the cutting load during drilling was measured.

- cutting conditions -

• Material to be cut: SUS304
• Cutting speed (peripheral speed) Vc = 60 m / min
• Feed rate f = 0.15 mm / rev

The measurement of the cutting load was carried out by placing the material to be cut on a measuring tool (cutting dynamometer of Kistler Japan) and cutting the material to be cut from above, measuring the axial load applied to the measurement implementation.

The result is in 6 shown. As in 6 In Example 1, the cutting load was reduced by approximately 300 Kgf · cm as compared to Sample 2. Further, the fluctuation of the cutting load in the sample 2 was about 300 Kgf · cm, while the fluctuation of the cutting load in the sample 1 was slightly less than 200 Kgf · cm, and thus smaller.

Further, in Sample 3, the cutting load peak in the initial stage of cutting is increased to approximately 1500 Kgf · cm, whereas in Sample 1, the upper limit of the cutting load is approximately 1200 Kgf · cm, and from the initial stage of cutting to Completion of the processing is stable, wherein the fluctuation of the cutting load during processing is also smaller than in the sample 3.

The result of the evaluation test indicates the effectiveness of changing the drill axis width of a honing face and a negative chamfer in the view perpendicular to the drill axis with respect to the position of a cutting edge, the honing face and the negative chamfer being provided to reinforce the cutting edge.

LIST OF REFERENCE NUMBERS

1

drill

2

main body

3

spiral

4

sloping surface

5

flank surface

6

cutting edge

6a

Dilution partial cutting edge

6b

peripheral cutting edge

6b-1

recessed-arcuate cutting part

6b-2

protruding-arcuate cutting part

7

dilution part

8th

edge

9

shaft

10

honing

11

negative phase

Claims (3)

A drill bit comprising: a diluting part formed at a turning center, and a cutting edge comprising a diluting part cutting edge formed on the diluting part and a recessed arcuate cutting part adjoining an outside end of the diluting part cutting edge, wherein a Honing surface or a negative chamfer is formed over the entire length of the cutting edge, and wherein the drill axis width of the honing surface or the negative chamfer in a view perpendicular to the drill axis gradually increases from the center of rotation to the outer end of the diluting part, gradually from the outer end the thinning part cutting edge becomes smaller toward a middle point of the recessed-arc shaped cutting part and gradually becomes larger from the middle point to the outer end of the cutting edge. A drill according to claim 1, wherein the drill axis width of the honing face or the negative bevel is 0.02 mm or 0.06 mm in the view perpendicular to the drill bit axis. A drill according to claim 1 or 2, wherein the radius of curvature of the recessed-arc shaped cutting part is set to 0.5 times the drill diameter or more.

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