JP2002200511A - Burnishing drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem wherein special grinding is required for regrinding for maintaining the length of a small diameter part. SOLUTION: By forming cutting edge lands 8 and 8a and finishing lands 9 and 9a on a rotating direction front side of small diameter lands 6 and 6a of the small diameter part 3 and a rotating direction rear side, respectively, providing separation grooves 10 and 10a in the small diameter lands 6 and 6a between the cutting edge lands 8 and 8a and the finishing lands 10 and 10a and forming the cutting edge lands 8 and 8a provided on the small diameter part 3 and the separation grooves 10 and 10a so as to extend to a large diameter part 2, a grinding wheel for grinding end faces at tips of the large diameter lands 5 and 5a enforces regrinding without damaging the cutting edge lands 8 and 8a by non-contact with the cutting edge lands 8 and 8a separated by the separation grooves 10 and 10a, even if ordinary cylindrical and plane grinding are enforced, when regrinding the large diameter lands 5 and 5a of the large diameter part 2 by the same amount as regrinding amount of the small diameter part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burnishing drill, and more particularly, to an improvement of a burnishing drill which performs finishing at the same time as drilling a stepped hole, so as to improve re-grinding workability and tool life. Related to burnishing drills.

[0002]

2. Description of the Related Art [Prior art of stepped holes] Conventionally, as a method of providing a sink seat of a screw head, a surface seat of a boss, or forming a stepped hole in a drilled hole provided in a work material by a drill, (1) The already drilled hole is additionally machined with a boring tool. (2) Using a step drill having a small-diameter portion on the distal end side and a large-diameter portion on the base end side (chuck side), drilling of a small-diameter hole and counterboring of a large-diameter hole are performed simultaneously. Two methods have been used.

According to the former method, two drills having a large diameter and a small diameter are required, and the operation is performed in two steps, and the processing time is long. According to the latter method, there is no such a defect in so-called one-shot drilling, but the following defect is present when re-grinding a drilling tool due to continuous use (wear, deterioration of the finished surface, etc.).

The latter step drill is, as shown in the side view of FIG. 31 (a), the tip view of FIG. 32 (a), and the end view of the large diameter portion taken along the line AA in FIG. 32 (b). a is composed of a large-diameter portion b on the base end side and a small-diameter portion c on the front end side having a predetermined length w corresponding to the shape of the hole to be machined, and two chip discharge grooves d and d are formed on the outer peripheral portion of the tool body a. Formed two large-diameter and small-diameter lands e, e,
f and f are provided respectively. A cutting edge g, g is provided at a tip end surface of the small diameter portion c at a rotation direction side edge of the small diameter land f, f facing the chip discharge groove d, d, and a tip end surface of the large diameter portion b, A large-diameter land e facing the chip discharge groove d, d,
The cutting blades h and h are provided on the edge in the rotation direction of e. At the time of re-grinding of the tool body a after continued use, the small-diameter portion c
Because there is a basic condition that the length w is the same length, FIG.
As shown in FIG. 1 (b), the small diameter portion c and the large diameter portion b had the disadvantage that the tip end faces had to be ground by the same grinding amount x, x (y, y).

[Prior art of drilling finish] Conventionally, as a method for finishing a work material simultaneously with drilling, (1) drilling a pilot hole and then finishing with a reamer. (2) Simultaneous preparation and finishing of a prepared hole with a so-called burnishing drill. Two methods have been used.

According to the former method, a drill and a reamer are used.
In addition to the necessity of using a working tool, there are disadvantages that the work is performed in two steps and the working time is long. According to the latter method, there is no such defect in so-called one-shot drilling, but the following defect is present when re-grinding a drilling finish tool by continuous use.

As shown in the side view of FIG. 33, the tip view of FIG. 34 (a), and the sectional view taken along the line BB of FIG. 34 (b), the latter burnishing drill has two strips on the outer periphery of the tool body a. And two lands e, e are provided. In the middle of the outer periphery of each land e, e, a flank surface j, j which is lower than the outer peripheral cylindrical surface (circle circumscribed circle and also a hole to be cut) of the tool body a shown by a dashed line is formed. , E, the cutting blade lands k, k are provided on the front side in the rotation direction, and the finishing lands m, m are provided on the rear side. A cutting edge g, g is provided at a tip end surface of the tool body a on the rotation direction side edge of the cutting edge land k, k facing the chip discharging groove d, d, and an edge on the chip discharging groove d, d side. Are provided with cutting edge margins (circumferential blades) n, n,
Further, finishing surfaces o, o are provided at the top ends of the finishing lands m, m adjacent to the flank surfaces j, j. At the time of re-grinding after continuous use, the cutting edge g, g of the tip end face of the tool body a
Was mainly ground.

[Prior Art of Combination Drill of Step Drill and Burnishing Drill] As described above, the step drill and the burnishing drill have their respective features, and a stepped burnishing drill combining these elements is also partially used. Have been. This stepped burnishing drill is shown in a side view in FIG. 35, a front view in FIG. 36 (a), and a cross-sectional view taken along the line C-C in FIG. 36 (b). A large diameter portion b on the end side and a predetermined length w corresponding to the shape of the hole to be machined
And two small-diameter lands e, e, f, f formed by forming two chip discharge grooves d, d in the outer peripheral portion of the tool body a. I have. Cutting edges g, g are provided on the tip end surface of the small diameter portion c at the rotation direction side edges of the small diameter lands f, f of the chip discharge grooves d, d, and the large diameter portion b
, And the cutting edges h, h are provided on the rotation-direction side edges of the large-diameter lands e, e facing the chip discharge grooves d, d.
Further, the stepped burnishing drill has a configuration of a step drill and also has a configuration of a burnishing drill. That is, a flank j is formed at an intermediate portion of the small-diameter lands f of the small-diameter portion c, and cutting lands k and k are provided on the front side in the rotational direction, and finishing lands m and m are provided on the rear side. And the chip discharge grooves d, d in the cutting blade lands k, k.
A cutting edge margin n, n is provided on the side edge, and a finishing surface o,
o is provided.

When re-grinding the stepped burnishing drill, the tip end face of the tool body a is ground and
In order to maintain the length w of the small diameter portion c at a predetermined length, the tip end surface of the large diameter portion b is also ground, but the large diameter land e of the large diameter portion b,
The grinding shape of e must be the same as the flank j, j (including the cutting edge lands k, k, the finishing lands m, m, etc.) provided on the small diameter portion c. Therefore, the large-diameter lands e and e of the large-diameter portion b
The grinding portion (shaving allowance) of the tip end surface of the surface is uneven (high cutting edge land k, k;
j), the damage of the cutting edge margins n, n provided on the cutting edge lands k, k occurs in the ordinary cylindrical grinding,
Cylindrical grinding for simple work is not possible and special partial grinding is required, or flank faces j and j must be formed separately while paying attention to the cutting edge margins n, n, and re-grinding work is troublesome and costly It had the disadvantage of being up.

[0010]

SUMMARY OF THE INVENTION The present invention provides a burnishing drill capable of performing simple re-grinding such as cylindrical grinding and surface grinding.

[0011]

SUMMARY OF THE INVENTION According to the present invention, in view of the problem that a special grinding is required for re-grinding a large-diameter portion while maintaining the length of a small-diameter portion based on the above conventional technique, the tool body is It consists of a small-diameter part at the distal end and a large-diameter part at the base end, chip discharge grooves are formed in the small-diameter part and the large-diameter part, and large-diameter lands and small-diameter lands are formed. A cutting land is formed at the front end side in the rotation direction of the small diameter land of the small diameter portion, and a finishing land is formed at the rear end side in the rotation direction, and the cutting land and the finishing land are formed. The separation groove is provided in the small-diameter land between the small-diameter portions, and the cutting edge land and the separation groove provided in the small-diameter portion are formed so as to extend to the large-diameter portion. When re-grinding large-diameter lands, carry out with simple cylindrical and surface grinding The grinding wheel that grinds the tip end face of the large-diameter land is in non-contact with the cutting edge land separated by the separation groove, and performs re-grinding without damaging the cutting edge margin of the cutting edge land. Solve.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The burnishing drill having a stepped hole according to the present invention has improved regrinding workability after continuous use, and is partially referred to as a subbrand stepped burnishing drill in the present specification.

As shown in FIGS. 1 and 2, a tool body 1 of a subbrand stepped burnishing drill according to the present invention comprises a large-diameter portion 2 at a proximal end and a small-diameter portion 3 at a distal end. Is the same diameter as the counterbore of the stepped hole (the large diameter hole at the surface with respect to the small diameter basic hole at the deep portion), and the small diameter portion 3 is the small diameter basic hole at the deep portion (tip) of the stepped hole. It is the same diameter and size as. On the outer periphery of the tool body 1 in which a small-diameter portion 3 having a predetermined length W is integrally formed at the end of the large-diameter portion 2, two linear chip discharge grooves 4 and 4 a are formed to form two large-diameter and small-diameter chips. The lands 5, 5a, 6, and 6a are provided respectively. The basic configuration for drilling such stepped holes corresponds to the conventional step drill shown in FIG. 31 and the like.

In the middle of the outer periphery of the small diameter lands 6 and 6a of the small diameter portion 3, flat flank surfaces 7 and 7a which are low with respect to the circumscribed circle of the small diameter portion 3 (refer to the prior art) are formed. Cutting lands 8 and 8a are provided on the front side, and finishing lands 9 and 9a are provided on the rear side. In addition, the cutting blade lands 8, 8a and the finishing lands 9,
The outer surface of 9a is, for example, a narrow arc surface having a width of less than 1 mm. Further, as shown in FIGS. 1 and 2 and FIGS. 3 and 4, separation grooves 10 and 10a are formed in the flank surfaces 7 and 7a in the vicinity of the rotational direction rear side of the cutting edge lands 8 and 8a to perform the drilling action. Separation of the cutting blade lands 8, 8a and the finishing lands 9, 9a of the vanish action (discontinuity)
In addition, the cutting edge lands 8, 8a and the separation grooves 10, 10a provided on the small diameter portion 3 are formed to extend to the large diameter portion 2.

The cutting edge lands 8, 8a and the separation grooves 10, 10a formed on the large diameter portion 2 have the same shape as those formed on the small diameter portion 3, and are formed on the large diameter portion 2. The cutting land 8, 8 a is lower than the outer peripheral surface (circumferential circle) of the large diameter portion 2. The flank surfaces 7 and 7a and the finishing lands 9 and 9a provided on the small-diameter portion 3 are not formed on the large-diameter portion 2 at all. The flank faces 7 and 7a and the finishing lands 9 and 9a are formed by grinding the tip end face.

As shown in FIGS. 1 and 2, cutting edges 11 and 11a are provided on the tip end surface of the small diameter portion 3 and on the rotation side edges of the cutting edge lands 8 and 8a facing the chip discharge grooves 4 and 4a. The flank 7, 7a (finish land 9, 9a) on the rear side in the rotation direction and the separation grooves 10, 10
a, and a cutting edge margin (peripheral blade) 12 is provided on the cutting edge lands 8, 8a extending from the small diameter portion 3 to the large diameter portion 2 in the rotation direction side edges of the chip discharge grooves 4, 4a. , 12a.

A cutting edge is provided at the tip end face of the large-diameter portion 2 at the rotation-direction side edge of the large-diameter lands 5, 5a facing the chip discharge grooves 4, 4a.
13 and 13a, and cutting edge margins 14 and 14a are provided on the rotation direction side edges of the chip discharge grooves 4 and 4a.

The finishing lands 9 and 9a provided on the rear side in the rotation direction of the small diameter lands 6 and 6a of the small diameter portion 3 are as follows.
Finishing surfaces (blades) 15, 15a are provided at the top ends of the finishing lands 9, 9a following the flank surfaces 7, 7a.

Next, the basic cutting and piercing action of the burnishing drill (subbrand stepped burnishing drill) according to the present invention will be described. By pressing the rotating tool body 1 against the work material, the cutting blades 11, 11 on the distal end face of the small-diameter portion 3 are pressed.
a performs cutting and drilling, and the cutting edges 12 and 8a of the cutting edge lands 8 and 8a perform auxiliary cutting (guide, centering, etc.) by slidingly contacting the inner peripheral surface of the hole to be cut. At the same time as the cutting drilling by the cutting blades 11 and 11a, the finishing lands 9 and 9a are formed on the inner peripheral surface of the hole to be drilled with plastic deformation, following the cutting blade margins 12 and 12a of the cutting blade lands 8 and 8a. The finishing surfaces 15 and 15a are in sliding contact with each other to apply a burnishing effect to the hole to be machined.

Then, when the drilling by the cutting blades 11, 11 a and the like progresses and drills a predetermined depth equal to the length W of the small diameter portion 3,
The cutting blades 13 and 13a on the tip end face of the large diameter portion 2 start contacting the surface of the workpiece, and drill a large diameter counterbore on the outer peripheral side of the small diameter drilled hole (basic hole). The drilling of the counterbore is performed by cutting the large-diameter lands 5 and 5a in addition to the cutting blades 13 and 13a at the end face of the large-diameter portion 2.
The cutting edge margins 14 and 14a of FIG. Then, when the required amount (depth) of the basic hole and the counterbore hole is completed, the depth of the basic hole becomes the same as the length W of the small diameter portion 3 of the tool body 1.

Next, the re-grinding operation of the burnishing drill according to the present invention will be described. In the re-grinding due to the continuous use of the tool body 1, the cutting edges 11, 11a and the cutting edges 13, 13a on the tip end surfaces of the small-diameter portion 3 and the large-diameter portion 2 are mainly re-ground, but the small-diameter portion 3 has a predetermined length W. , The re-grinding amounts of the small diameter portion 3 and the large diameter portion 2 are made the same.

The re-grinding of the small-diameter portion 3 is performed by a conventional grinding method, and the re-grinding of the large-diameter portion 2 is also performed by a simple grinding such as a conventional cylindrical or surface grinding in the burnishing drill according to the present invention. That is, the re-grinding of the cutting blades 13 and 13a at the distal end of the large-diameter portion 2 is performed by cylindrical grinding or surface grinding, so that the re-grinding of the cutting blades 13 and 13a is performed. , 13a are retracted to the proximal side by the same amount as the retraction amounts of the cutting edges 11, 11a of the small diameter portion 3. At that time, the cutting lands 8, 8a extending from the large-diameter portion 2 to the large-diameter portion 2 and the large-diameter lands 5, 5a of the large-diameter portion 2 so that the re-grinding portion M is indicated by cross-hatching in FIG. Is the separation groove
Since they are separated by 10 and 10a, the grinding wheel for re-grinding the tip end surfaces of the large-diameter lands 5 and 5a does not come into contact with the cutting-edge lands 8 and 8a extending to the large-diameter portion 2.

The grinding wheel cuts the large-diameter lands 5 and 5a so as to have the same shape as the flank surfaces 7 and 7a of the small-diameter lands 6 and 6a in the small-diameter portion 3, and has a larger diameter than the flank surfaces 7 and 7a. (Projecting) to form the finishing lands 9 and 9a. At this time, depending on the contact angle and position of the grinding wheel with the large-diameter lands 5, 5a, the finishing lands 9, 9a are broken at the boundary with the large-diameter portion 2, which is the base end side of the finishing lands 9, 9a. Could be done. However, suppose that the finishing lands 9, 9a
, The finishing land 9 that is ground and broken,
Since 9a is a small amount and is on the surface side of the basic hole in the drilled hole, there is no practical problem even if the burnishing action of the portion is insufficient. Alternatively, the grinding wheel may be carefully abutted, or special partial grinding may be performed after ordinary grinding, or the second separation groove may be formed in the finishing lands 9, 9a as described later.
May be provided immediately before. Furthermore, preferably, FIGS.
As will be described later as a zero embodiment, second separation grooves 30, 30a are provided near the front side in the rotational direction of the finishing lands 9, 9a.

Hereinafter, another embodiment of the burnishing drill with a subbrand step according to the present invention will be described. The chip discharge grooves 4, 4a and the large-diameter, small-diameter lands 5, 5a, 6, 6a formed in the large-diameter portion 2 and the small-diameter portion 3 of the tool body 1 have been described as being linear, but are shown in FIGS. Like things, or Figure 16-
As shown in FIG. 20, it may be inclined or spiral. 6 to 10 or FIGS.
In order to supply the lubricating oil to the hole to be machined, oil supply holes 20 and 20a may be provided vertically through the tool body 1 as shown in FIG. Are opened in the small-diameter lands 6, 6a. In the embodiment in which the oil supply holes 20 and 20a are provided, the flank surfaces 7 and 7a provided on the outer surfaces of the small-diameter lands 6 and 6a are formed as a plurality of continuous planes. FIG.
25 to 25, the flank surfaces 7 and 7a are not flat,
It may be an arc surface (partially cylindrical surface). In this case,
The finishing lands 9 and 9a may be broken at the time of re-grinding, but there is no practical problem as described above. In this manner, the surface shapes of the cutting edge lands 8, 8a provided on the small diameter lands 6, 6a of the small diameter portion 3 and the flank surfaces 7, 7a lower than the finishing lands 9, 9a can be appropriately changed.

Next, a preferred configuration of the finishing lands 9, 9a will be described. In the above, in the formation of the finishing lands 9 and 9a provided on the small diameter lands 6 and 6a of the small diameter portion 3, the finishing lands 9 and 9a are made continuous with the flank surfaces 7 and 7a.
As described in the operation section, the finishing lands 9 and 9a were broken at the time of re-grinding, or special grinding was required even if there was no practical problem. Therefore, the flank surfaces 7 and 7a may be separated from the finishing lands 9 and 9a in the same manner as the main configuration of the present invention in which the cutting edge lands 8 and 8a are separated from the flank surfaces 7 and 7a via the separation grooves 10 and 10a. . That is, as shown in FIGS. 26 to 30, the second separation grooves 30, 30a are formed in the flank surfaces 7, 7a between the cutting blade lands 8, 8a and the separation grooves 10, 10a and the finishing lands 9, 9a. The flank surfaces 7, 7a and the finishing lands 9, 9a are separated (discontinued) by the second separating grooves 30, 30a, and the second separating grooves 30, 30a formed in the small diameter portion 3 and the finishing lands 9, 9a are further separated. An extension is formed on the large diameter portion 2. When the second separation grooves 30, 30a and the finishing lands 9, 9a formed in the small diameter portion 3 are formed to extend to the large diameter portion 2,
Since the extension lands are formed in the same shape, the finishing lands 9 and 9a are lower than the circumscribed circle of the large diameter portion 2. With this configuration, at the time of re-grinding, similarly to the case where the cutting blade lands 8, 8a are separated from the flank surfaces 7, 7a and the grinding wheel is re-ground to the cutting blade lands 8, 8a in a non-contact manner, the finishing lands 9, The lands 9 and 9a are also separated from the flank surfaces 7 and 7a, so that the grinding lands are not in contact with the lands 9 and 9a, thereby preventing breakage of the lands 9 and 9a.

The positional relationship and the like in FIGS. Subsequent to the cutting edge lands 8, 8a on the front side in the rotation direction, separation grooves 10, 10a are located on the rear side near the cutting edge lands 8, 8a, and the flank surfaces 7, 7a are interposed therebetween.
The second separation grooves 30, 30a and the finishing lands 9, 9a are located, and the positions of the second separation grooves 30, 30a with respect to the finishing lands 9, 9a are located near the front of the finishing lands 9, 9a. Groove 30, 30
a is located. As a result, the cutting blade lands 8, 8a, the flank surfaces 7, 7a and the finishing lands 9, 9a are separated by the separation grooves 10, 10a and the second
They are separated by separation grooves 30, 30a. It is needless to say that this configuration can be applied to the above-mentioned burnishing drill, such as one having an oil hole and having a twist.

[0027]

In short, according to the present invention, the tool body 1 is composed of the small diameter portion 3 at the distal end and the large diameter portion 2 at the base end, and the chip discharge grooves 4, 4a are formed in the small diameter portion 3 and the large diameter portion 2. As a result, the large-diameter lands 5, 5a and the small-diameter lands 6, 6a are respectively formed, so that chips and chips of the work material are discharged from the chip discharge grooves 4, 4a, and the small-diameter portion 3 and the large-diameter portion 2 Cutting edge 11, 11a, cutting edge 1 at the tip
Since cutting blades 3 and 13a are formed respectively, cutting blades 11 and 11a of small diameter portion 3 are formed.
Can be used to drill a basic hole, and a counterbore hole can be drilled with the cutting blades 13 and 13a of the large diameter portion 2, and a basic hole can be drilled with a stepped hole having a predetermined depth (length W of the small diameter portion 3). In addition, the cutting blade lands 8, 8a are provided on the small diameter lands 6, 6a of the small diameter portion 3 on the front side in the rotation direction.
Since the finishing lands 9 and 9a are formed on the rear side in the rotation direction, the basic holes drilled mainly by the cutting blades 11 and 11a can be subjected to burnishing by the finishing lands 9 and 9a. Separation grooves 10 and 10a are provided on the outer periphery of the small-diameter lands 6 and 6a in the vicinity of the rotation-direction rear side of the cutting blade lands 8 and 8a.
Since the cutting edge lands 8, 8a and the separation grooves 10, 10a provided on the large-diameter portion 2 are formed so as to extend to the large-diameter portion 2, when the large-diameter portion 2 is re-ground by an amount corresponding to the shortened small-diameter portion 3 at the time of re-grinding, Even if the large-diameter lands 5 and 5a of the diameter portion 2 are re-ground by a usual grinding method, the grinding wheel is not in contact with the cutting blade lands 8 and 8a separated by the separation grooves 10 and 10a. Since the tip end face of 5a can be cut, re-grinding can be performed very easily without damaging the cutting edge lands 8, 8a.

Since the flank surfaces 7 and 7a are formed in the middle portion of the small-diameter lands 6 and 6a of the small-diameter portion 3 and the cutting lands 8, 8a and the finishing lands 9 and 9a are provided, respectively, the cutting blades 11, 11a and The plastic deformation inner peripheral surface of the hole to be cut by the cutting edge margins 12 and 12a can be subjected to vanishing by the finishing lands 9 and 9a which rotate subsequently to the flank surfaces 7 and 7a.

Since the flank surfaces 7 and 7a lower than the cutting edge lands 8 and 8a and the finishing lands 9 and 9a are formed as a plane, a plurality of planes or a cylindrical surface, the large-diameter lands 5 and 5a are reground to form the flank 7, The cutting operation for forming 7a can be easily performed by a usual re-grinding method.

Since the flank surfaces 7 and 7a are provided with the separation grooves 10 and 10a, the separation state of the cutting edge lands 8 and 8a and the finishing lands 9 and 9a can be clarified and the re-grinding operation can be easily performed.

Second separation grooves 30, 30a are provided on the outer periphery of the small diameter lands 6, 6a near the front side in the rotation direction of the finishing lands 9, 9a, and the finishing lands 9, 9a and the second separation grooves provided on the small diameter portion 3 are provided. Since the grooves 30, 30a are formed to extend to the large diameter portion 2, when the large diameter portion 2 is re-ground in accordance with the shortening of the small diameter portion 3, the large diameter lands 5, 5a of the large diameter portion 2 are subjected to ordinary grinding. Even if re-grinding by the method, the grinding wheel can perform re-grinding very easily without contactlessly damaging the finishing lands 9, 9a separated by the second separation grooves 30, 30a. The effect is enormous.

[Brief description of the drawings]

FIG. 1 is a side view of a burnishing drill provided with a separation groove in the vicinity of a cutting edge land according to the present invention (a burnishing drill with a sub-brand step).

FIG. 2 is a front view of FIG.

FIG. 3 is a sectional end view taken along the line AA of FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is a view showing a re-grinding portion of a large diameter portion.

FIG. 6 is a side view of a burnishing drill with an oil hole.

FIG. 7 is a front view of FIG. 6;

8 is a cross-sectional end view taken along the line CC in FIG. 6;

FIG. 9 is a sectional view taken along line DD of FIG. 6;

FIG. 10 is a view showing a re-grinding portion of a large diameter portion.

FIG. 11 is a side view of a burnishing drill having a twist.

FIG. 12 is a front view of FIG. 11;

FIG. 13 is a sectional end view taken along the line EE of FIG. 11;

FIG. 14 is a sectional view taken along line FF of FIG. 11;

FIG. 15 is a view showing a re-grinding portion of a large diameter portion.

FIG. 16 is a side view of a burnishing drill with a twist and an oil hole.

FIG. 17 is a front view of FIG. 16;

FIG. 18 is a sectional end view taken along line GG of FIG. 16;

FIG. 19 is a sectional view taken along the line HH in FIG. 16;

FIG. 20 is a view showing a re-grinding portion of a large diameter portion.

FIG. 21 is a side view of a burnishing drill in which a flank of a small diameter portion is an arc surface.

FIG. 22 is a front view of FIG. 21;

FIG. 23 is a sectional end view taken along the line II of FIG. 21;

FIG. 24 is a sectional view taken along the line JJ of FIG. 21;

FIG. 25 is a view showing a re-grinding portion of a large diameter portion.

FIG. 26 is a side view of a burnishing drill provided with a second separation groove near a finishing land.

FIG. 27 is a front view of FIG. 26;

FIG. 28 is a sectional end view taken along the line KK of FIG. 26;

FIG. 29 is a sectional view taken along line LL of FIG. 26;

FIG. 30 is a view showing a re-grinding portion of a large diameter portion.

31A and 31B are diagrams of a conventional step drill, in which FIG. 31A is a side view, and FIG. 31B is a diagram for explaining a reduction in length during re-grinding.

FIG. 32 (a) is a tip view of the step drill of FIG. 31,
(B) is an AA sectional end view of the large diameter portion.

FIG. 33 is a side view of a conventional burnishing drill.

34A is a front view of the burnishing drill shown in FIG. 33, and FIG. 34B is a cross-sectional end view taken along the line BB.

FIG. 35 is a side view of a conventional stepped burnishing drill.

36 (a) is a front view of the stepped burnishing drill of FIG. 35, and FIG. 36 (b) is a cross-sectional view taken along CC.

[Explanation of symbols]

 1 Tool body 2 Large diameter part 3 Small diameter part 4, 4a Chip discharge groove 5, 5a Large diameter land 6, 6a Small diameter land 7, 7a Relief surface 8, 8a Cutting blade land 9, 9a Finishing land 10, 10a Separation groove 11, 11a Cutting blade 13, 13a Cutting blade 30, 30a Second separation groove

Continued on the front page (72) Inventor Yuji Sato 6-31 Takaracho, Kariya-shi, Aichi Japan Carbide Co., Ltd. F-term (reference) 3C037 AA08 BB00 DD03

Claims (5)

[Claims] The tool body includes a small-diameter portion at a distal end portion and a large-diameter portion at a base end portion, a chip discharge groove is formed in the small-diameter portion and the large-diameter portion, and a large-diameter land and a small-diameter land are respectively formed. A drill having a cutting edge and a cutting edge formed at the tip of the small-diameter portion and the large-diameter portion, respectively. The cutting blade land is provided on the small-diameter land of the small-diameter portion in the rotation direction front side, and the finishing land is provided on the rotation direction rear side. A separation groove is provided on the outer periphery of the small-diameter land in the vicinity of the rotational direction rear side of the cutting land, and the cutting land and the separation groove provided on the small-diameter portion are formed to extend to the large-diameter portion. Burnishing drill. 2. The burnishing drill according to claim 1, wherein a flank is formed at an outer peripheral intermediate portion of the small diameter land of the small diameter portion, and a cutting edge land and a finishing land are provided respectively. 3. The burnishing drill according to claim 2, wherein the flank lower than the cutting edge land and the finishing land is a plane, a plurality of planes or a cylindrical surface. 4. The burnishing drill according to claim 3, wherein a separation groove is provided on the flank. 5. A second separation groove is provided on an outer periphery of a small-diameter land near a rotation direction front side of a finishing land, and the finishing land and the second separation groove provided on a small-diameter portion are formed to extend to a large-diameter portion. The burnishing drill according to claim 1, 2, 3, or 4, wherein: