JP2001287110A - Drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the wear of a margin part 6 by surely and efficiently feeding a cutting fluid to the margin part 6. SOLUTION: Chip evacuation slots 2 are formed in the circumference of a tip part of a nearly cylindrical drill body 1 rotated around an axis O, a cutting blade 4 is formed on the ridge part on the tip side of a wall surface 2A facing to the drill rotation direction T of each of the chip evacuation slots 2, the margin part 6 of which circumferential surface 6a forms a cross- sectionally circular arc centering the axis O with an outside diameter D nearly equal to the cutting blade 4 is formed on the edge part on the drill rotation direction T side of each land part 5 formed in the circumferential direction between the chip evacuation slots 2, and a feeding slot 11 of the cutting fluid is formed on the circumferential surface 6a of each of the margin parts 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill for drilling a workpiece with a cutting blade formed at the tip of a drill body rotated about an axis.

[0002]

2. Description of the Related Art As such a drill, for example, FIG.
Or a two-edged twist drill as shown in FIG. 7 is generally known. In the twist drill shown in these figures, a pair of chip discharge grooves 2 and 2 are formed around the distal end of a substantially cylindrical drill body 1 formed of a hard material such as steel or cemented carbide. The tip side of the wall surface 2A of each chip discharge groove 2 facing the drill rotation direction T side is formed so as to be twisted rearward in the drill rotation direction T at the time of machining as it goes to the rear end side symmetrically with respect to the axis O of FIG. At the ridge, that is, at the intersection ridge line between the wall surface 2A and the tip flank 3 of the drill body 1, there is formed a cutting edge 4 which is inclined toward the rear end side at a predetermined cutting edge angle toward the outer peripheral side. I have. Note that a thinning surface 3a is formed on the rear side of the tip flank 3 in the drill rotation direction T, so that the inner peripheral side portion of the cutting blade 4 is on the axis O side of the tip flank 3, that is, The thinning blade 4a is bent toward the center of rotation of the drill to form a thinning blade 4a.
A chisel blade 4b is formed on the axis O where the thinning blades 4a, 4a intersect.

On the other hand, the portion of the tip of the drill body 1 which is left in the circumferential direction between the chip discharge grooves 2 and 2 is a land 5, so that this land 5 is
Is formed so as to be twisted around the axis O in accordance with the torsion of the cutting edge 4a.
The margin portion 6 having an outer diameter substantially equal to the outer diameter D and having an arc-shaped cross section centered on the axis O makes the circumferential width uniform,
It is formed so as to be twisted toward the rear side in the drill rotation direction T toward the rear end side in accordance with the twist of the chip discharge groove 2 and the land portion 5. Note that the outer peripheral surface 5 of the land portion 5 behind the margin portion 6 in the drill rotation direction T
a is provided with an outer diameter slightly smaller than the outer diameter D so as to be recessed one step toward the inner peripheral side with respect to the outer peripheral surface 6a of the margin portion 6. Further, a supply hole 8 for a cutting oil is formed in the drill main body 1 from the shank portion 7 at the rear end toward the front end side, and is opened at the front end flank 3. In the illustrated example, a pair of supply holes 8, 8 are formed in the drill body 1 so as to be twisted around the axis O in accordance with the chip discharge grooves 2, 2, and the tips thereof are respectively the cutting blades. The above-mentioned flank 3 is located adjacent to the rear side of the drill rotation direction T of the fourth and fourth drills.
It is opened to.

However, in the drill constructed as described above, the drill body 1 is attached to the rotating shaft of the machine tool via the shank portion 7 and is sent out to the tip side in the direction of the axis O while being rotated about the axis O. Thus, the workpiece is scraped by the cutting blades 4 and 4 and is used to perform a boring process on the workpiece. At this time, the margin portion 6 guides the drill body 1 straight along the axis O by sliding its outer peripheral surface 6a into contact with the inner periphery of the processing hole formed by the cutting edge 4. To play. At the time of this drilling, the cutting oil sent from the machine tool through the supply hole 8 causes the tip flank 3
To cool and lubricate the cutting edge 4 and the cut portion at the bottom of the hole.

[0005]

However, when such a drill is used for a long period of time, it is inevitable that the margin portion 6 is worn due to sliding contact with the inner periphery of the drilled hole. When the margin portion 6 is worn in this way, there arises a problem that cutting resistance at the time of drilling increases. However, in this point, in the conventional drill, the cutting oil is supplied from the flank 3 through the supply hole 8 as described above, thereby cooling and lubricating the cutting edge 4 and also cooling the margin portion 6. Although the lubrication is performed to suppress the wear, the cutting oil supplied from the tip flank 3 at the tip of the drill body 1 into the machining hole is applied to the entire length of the tip of the drill body 1 inserted into the machining hole. It is difficult to spread over the margin portion 6 over the entire area. In particular, as the depth of the processing hole increases, the margin portion 6 is closer to the opening side of the processing hole.
Therefore, it becomes difficult to effectively cool and lubricate the cutting oil.

The present invention has been made in view of such circumstances, and provides a drill capable of reliably and efficiently supplying a cutting oil to the margin to suppress wear of the margin. It is intended to be.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems and achieve such an object, according to the present invention, a chip discharge groove is provided on the outer periphery of the tip of a substantially cylindrical drill body rotated about an axis. Forming a cutting edge at the tip side edge of a wall of the chip discharge groove facing the drill rotation direction, and a land portion formed between the chip discharge grooves in the circumferential direction on the drill rotation direction side. On the edge, an outer peripheral surface was formed with a margin portion having an outer diameter substantially equal to that of the cutting blade and having an arc-shaped cross section centered on the axis, and a supply groove for a cutting oil was formed on the outer peripheral surface of the margin portion. It is characterized by the following. Therefore, in the drill configured as described above, the cutting oil is surely spread to the margin portion through the supply groove and supplied between the outer peripheral surface and the inner periphery of the processing hole. Also on the part side, the margin part can be efficiently cooled and lubricated, and its wear can be reduced.

Here, if the distal end of the supply groove is formed so as to open to the distal flank of the drill body and to extend toward the inner peripheral side of the distal flank, particularly, the conventional drill is provided. When the cutting oil is supplied from the flank of the tip through the supply hole formed in the drill body, the cutting oil can be more efficiently supplied from the tip of the supply groove to the margin. If the size of the supply groove is too small, efficient supply of the cutting oil to the margin may be impaired.On the other hand, if the size is too large, the strength of the margin may deteriorate, There is a possibility that fine chips generated during the opening process may enter the supply groove and cause clogging. For this reason, this supply groove has a groove width of 0.02 to the outer diameter D of the cutting blade.
It is desirable to set the groove depth in the range of 0.10 × D and the groove depth in the range of 0.1 to 1.0 mm.

[0009]

1 to 3 show a first embodiment of the present invention.
However, since the basic configuration of the drill of this embodiment does not replace the conventional drill shown in FIGS. 5 to 7, the same reference numerals are used for common parts. To simplify the description. That is, in the drill of the present embodiment, cutting is performed on the outer peripheral surfaces 6a, 6a of the margin portions 6, 6 formed at the outer periphery of the distal end portion of the drill body 1 on the edge in the drill rotation direction T side of the land portions 5, 5. It is characterized in that oil supply grooves 11, 11 are formed. Accordingly, as the land portion 5 and the margin portion 6 are twisted rearward in the drill rotation direction T toward the rear end side in accordance with the twist of the chip discharge groove 2, the supply groove 11 is also similarly rearward. Are formed so as to be twisted toward the rear side in the drill rotation direction T.

Further, the supply groove 11 forms a margin portion 6 with the first margin portion 6A, which is located on the drill rotation direction T side and continues to the chip discharge groove 2 with the supply groove 11 interposed therebetween,
It is divided into a second margin portion 6B located on the rear side in the drill rotation direction T and connected to the outer peripheral surface 5a to which the land portion 5 is provided with relief. The second of the rotation direction T rear side
In this embodiment, the margin portion 6B is disposed so as to be located on a plane P extending parallel to the cutting edge 4 along the axis O at the tip of the drill body 1 as shown in FIG. Has been established.

Here, in the present embodiment, the supply groove 11
Has a substantially semicircular cross section perpendicular to the axis O as shown in FIG. 3, and its radius r is set in the range of 0.1 to 1.0 mm. Accordingly, in the supply groove 11, the groove depth d from the outer peripheral surface 6a of the margin portion 6 is also in the range of 0.1 to 1.0 mm like the radius r, and the groove width w
Is in the range of 0.2 to 2.0 mm. When the outer diameter of the cutting edge 4 of the drill is D, the supply groove 11
And the width A of the margin portion 6 is 0.08 to 0.15 × D
Is desirably set in the range of .0.
09 × D, wherein the widths B and C of the first and second margin portions 6A and 6B and the groove width w of the supply groove 11 are in the range of 0.02 to 0.10 × D, respectively. In this embodiment, the width B and the width C are made equal to each other so that the supply groove 11 is disposed at the center of the margin portion 6 in the circumferential direction, and the groove width w is also equal to these. B, C and groove width w are all 0.0
3 × D.

On the other hand, the supply groove 11 is opened at the tip flank 3 at the tip of the drill body 1, and the tip portion 11 a has a groove depth gradually decreasing toward the inner peripheral side parallel to the cutting blade 4. Then, it is formed so as to be cut relatively on the outer peripheral side of the tip flank 3. Here, the groove depth e at the outer peripheral end of the leading end 11a of the supply groove 11 is equal to the groove depth d at the margin 6 in the present embodiment, and is 0.1 to 0.1.
The inclination angle α of the groove bottom of the tip 11a with respect to the tip flank 3 of the groove bottom which rises as the groove depth of the tip 11a gradually becomes shallower toward the inner peripheral side is: The range is 1 to 15 °. Note that the length of the supply groove 11 from the tip 11 a is at least １ ／ or more of the length of the chip discharge groove 2.

In the drill constructed as described above,
The cutting oil supplied from the machine tool side into the machining hole through the supply hole 8 formed in the drill body 1 or supplied by being sprayed from the outside by a nozzle or the like toward the opening of the machining hole is supplied to the above-described cutting fluid. The margin portion 6 is surely extended to the margin portion 6 through the supply groove 11.
Can be efficiently cooled and a lubricating effect can be given, and the wear of the margin portion 6 due to the outer peripheral surface 6a slidingly contacting the inner periphery of the machined hole can be suppressed.
Therefore, even when used for a long period of time, it is possible to suppress an increase in cutting resistance due to wear of the margin portion 6, and
The drill body 1 is stably moved along the axis O by the margin portion 6.
And the wear of the margin portion 6 is suppressed, so that the drill body 1
Since the outer diameter D of the cutting edge 4 is also prevented from being reduced due to the wear of the margin portion 6 at the tip, it is possible to perform highly accurate drilling, and as a result, the life of the drill can be extended.

The wear of the margin portion 6 due to the sliding contact with the inner periphery of the drilled hole is caused by the drill of the margin portion 6 which first comes into sliding contact with the inner periphery of the drilled hole after the chip discharge groove 2 with the rotation of the drill body 1. It becomes larger on the rotation direction T side. On the other hand, in the present embodiment, the supply groove 11 is formed on the outer peripheral surface 6a of the margin portion 6 so that the margin portion 6 is adjacent to the first and second circumferential portions with the supply groove 11 interposed therebetween. It is divided into the second margin portions 6A and 6B. Therefore, even if the first margin portion 6A on the drill rotation direction T side wears, the second margin portion 6B on the rear side in the rotation direction T does not. A predetermined outer diameter can be maintained, thereby further extending the drill life. Moreover, these second margin portions 6
B is disposed so as to be located on the plane P extending parallel to the cutting edge 4 along the axis O as described above,
Of the second margin portion 6B
Accordingly, even when the drill body 1 is guided, an effect that balance can be easily obtained can be obtained.

In the present embodiment, the supply groove 11 is opened in the flank 3 of the distal end of the drill body 1, and the opened distal end 11a extends from the opening on the outer peripheral side toward the inner peripheral side. Has been. Therefore, especially when the supply hole 8 for the cutting fluid is formed in the inside of the drill body 1 as described above and supplied from the flank surface 3 to the machining hole, the cutting fluid supplied into the machining hole is provided. Can be reliably introduced into the supply groove 11 from the front end portion 11a and supplied to the margin portion 6. In addition, in the present embodiment, as the chip discharge groove 2 is formed to be twisted rearward in the drill rotation direction T toward the rear end side, the margin portion 6 and the supply groove 11 are similarly formed on the rear end side. , The cutting fluid introduced from the front end portion 11a can be sent to the rear end along with the rotation of the drill body 1 because the cutting fluid is introduced from the front end 11a. Efficient and reliable supply of cutting oil can be achieved.

In the present embodiment, the groove depth e at the outer peripheral end of the leading end 11a of the supply groove 11 is
The depth of the groove is equal to the groove depth d in the range of 0.1 to 1.0 mm.
Is set in the range of 1 to 15 °, this is because if the groove depth e is too large, the outer periphery of the tip end of the drill body 1 may be easily chipped, while if the groove depth e is too small, the above-described effect is obtained. If the inclination angle α is too large, the radial length of the distal end portion 11a opening to the distal flank 3 may be shortened, and the above-described effect may not be achieved. On the other hand, on the other hand, even if the length of the tip portion 11a is too long to increase the length, the effect is not so much improved. Therefore, it is desirable that the groove depth e and the inclination angle α of the leading end 11a of the supply groove 11 are set in the ranges of 0.1 to 1.0 mm and 1 to 15 °, respectively, as in the present embodiment. . In some cases, the tip 11 of the supply groove 11
a may not be formed so as to extend inward on the tip flank 3, but may be formed such that the supply groove 11 is open to the tip flank 3 with a cross-sectional shape formed on a plane orthogonal to the axis O. .

Further, in the present embodiment, the supply groove 11
And the groove depth d of 0.1 to 1.0 mm,
Although the groove width w is set in the range of 0.2 to 2.0 mm, and particularly with respect to the outer diameter D of the cutting edge 4, it is set to 0.03 × D so as to be in the range of 0.02 to 0.10 × D. If the groove depth d and the groove width w are too small, the cross-sectional area of the supply groove 11 is also small, and supply of a sufficient cutting oil may be impaired.
On the other hand, if the groove depth d or the groove width w is too large, fine chips generated during the drilling process enter the supply groove 11 to cause clogging, which also impairs the supply of the cutting oil. There is a fear. Therefore, as in the present embodiment, the groove depth d of the supply groove 11 is 0.1 to
It is preferable that the groove width w is set to be in the range of 0.02 to 0.10 × D with respect to the outer diameter D of the cutting edge 4.

Further, in the present embodiment, the supply groove 11 has a semicircular cross-section, and if the groove depth d and the groove width w are the same, a relatively large cross-sectional area of the supply groove 11 is secured, so that a more sufficient cutting fluid Can be obtained. In this embodiment, the supply groove 11 is semicircular in cross section, and the radius r is in the range of 0.1 to 1.0 mm, for the same reason as in the case of the groove depth d and the groove width w. However, instead of such a supply groove 11 having a semicircular cross section, a cross section of the same circular shape, an elliptical shape, or an oval shape may be used.

Further, instead of making the supply groove 11 circular in cross section as in the first embodiment, for example, the supply groove 11 is formed on the outer peripheral surface 6a of the margin portion 6 as in the second embodiment shown in FIG. May be formed in a triangular cross section. In the second embodiment, the same reference numerals are given to the same parts as those in the first embodiment and the conventional drill shown in FIGS. 5 to 7, and the description is omitted. Here, the triangle formed by the cross section of the supply groove 21 is a right-angled isosceles triangle whose right-angled corner is located on the groove bottom side in the present embodiment, and the groove depth d is the first. As in the first embodiment, the groove width is set in the range of 0.1 to 1.0 mm.
In the range of 2.0 mm, the outer diameter D of the cutting edge 4 is 0.02 mm.
０．１0.10 × D. In the present embodiment, the triangle formed by the cross section of the supply groove 21 is a right-angled isosceles triangle, and the included angle θ between the groove wall surfaces is 90 °. However, the included angle θ is in the range of 30 to 120 °. It is desirable to be set.

However, in the drill of the second embodiment configured as described above, the cross-sectional area of the supply groove 21 is smaller than that of the first embodiment, but the other is the first embodiment. The same effect as described above can be obtained, and the groove wall surface of the supply groove 21 and the margin portion 6 can be obtained.
Since the angle of intersection with the outer peripheral surface 6a can be made larger than that in the first embodiment, the strength at the intersection ridge line between the groove wall surface and the outer peripheral surface 6a of the margin portion 6 is ensured to further reduce wear and the like. The effect that the prevention can be surely obtained is also obtained.
In the present embodiment, the included angle θ of the groove side surface of the supply groove 21 is set.
Is in the range of 30 to 120 ° as described above. However, when the included angle θ exceeds this range, the groove depth d and the groove width are required to secure a sufficient sectional area in the supply groove 21. This is because w may become too large. Therefore, it is desirable that the included angle θ be set in the range of 30 to 120 ° as described above.

[0021]

As described above, according to the present invention,
The cutting oil can be reliably and efficiently supplied between the margin portion and the inner periphery of the machining hole through the supply groove formed on the outer peripheral surface of the margin portion. To prevent the increase of cutting force and guide the drill body stably.
Further, the drilling accuracy can be maintained at a high accuracy, and as a result, the life of the drill can be extended.

[Brief description of the drawings]

FIG. 1 shows a drill body 1 according to a first embodiment of the present invention.
It is a side view of a front-end | tip part.

FIG. 2 is a front view of the embodiment shown in FIG. 1 as viewed from a distal end side.

FIG. 3 is a sectional view taken along the line ZZ in FIG. 1;

FIG. 4 is a view corresponding to a ZZ sectional view in FIG. 1 showing a second embodiment of the present invention.

FIG. 5 is a side view showing a conventional drill.

6 is an enlarged side view of a tip portion of the drill shown in FIG.

FIG. 7 is an enlarged front view of the drill shown in FIG. 5 as viewed from a distal end side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drill main body 2 Chip discharge groove 3 Tip flank 4 Cutting edge 5 Land part 6 Margin part 6a Outer peripheral surface of margin part 8 Cutting oil supply hole 11, 12 Cutting oil supply groove 11a Tip of supply groove 11 O drill Axis line of the main body 1 T Drill rotation direction D Outer diameter of the cutting blade 4 d Groove depth of the supply grooves 11, 12 w Groove width of the supply grooves 11, 12 r Radius of a semicircle formed by the cross section of the supply groove 11 Supply groove 12 Angle of triangle formed by cross section of

Claims (3)

[Claims] 1. A chip discharge groove is formed on the outer periphery of a tip portion of a substantially cylindrical drill body that is rotated around an axis, and a cutting edge is formed on a tip side edge of a wall surface of the chip discharge groove facing the drill rotation direction. At the edge of the land portion formed between the chip discharge grooves in the circumferential direction at the drill rotation direction side, the outer peripheral surface has an outer diameter substantially equal to the cutting edge and a cross section centered on the axis. A drill, wherein a margin portion having an arc shape is formed, and a supply groove for a cutting oil is formed on an outer peripheral surface of the margin portion. 2. The drill according to claim 1, wherein a distal end of the supply groove is open to a distal flank of the drill body and extends toward an inner peripheral side of the distal flank. . 3. The supply groove has a groove width set in a range of 0.02 to 0.10 × D with respect to an outer diameter D of the cutting blade, and a groove depth of 0.1 to 0.1 × D. 3. The method according to claim 1, wherein the distance is set to 1.0 mm.
Drill described in.