JPS60221210A - Drill for cutting deep hole - Google Patents

Abstract

PURPOSE:To assure the straight movement of the bit of a drill, by protruding a tip portion of at least one of an inner and an outer cutting parts attached to the bit of the drill. CONSTITUTION:The tip portions 13 of cutting parts 12a-12c provided on the bit 1 of a drill are protruded almost triangularly. Cutting reaction forces act in two directions to protruded edges 13a, 13b adjacent to each other along the circumferential direction of the drill bit 1. As a result, one of two guide pads 9a, 9b is prevented from receiving the cutting reaction forces concentratedly. Furthermore, the drill bit 1 is kept from being displaced in the radial direction, so that the straight movement of the drill bit is assured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a drill comprising an outer cutting blade and an inner cutting blade for cutting and forming a deep hole in a metal workpiece.

(Prior art) Figures 7a and 7s show conventional examples.
is a cylindrical drill head, 28 to 2c are cutting blades fixed to the thick part of the tip of the drill head by brazing, etc., of which the cutting blade located on the positioning edge side is called the outer cutting blade 2a; The cutting blade located on the side is the inner cutting blade 2b
, 2c. These cutting blades 2a to 2c are shown in FIG.
As shown in FIG.
The inner edge 4 of the cutting edge portion 3 of the inner cutting blade 2b on the most axial center side is always on the top! - The inner edge 4 passes through the rotational axis 0 of the ril hesode 1, and the portion of the inner edge 4 that passes through the rotational axis O and extends rightward in the figure does not perform a cutting action, but is generally formed in manufacturing.

Furthermore, as shown in FIG.
A stepped portion 6 is formed, which is called a chip breaker, and has the function of finely dividing chips (chips) generated by cutting by the cutting edge portion 3 into appropriate intervals in the longitudinal direction. Chips are smoothly discharged from the hollow interior of the head 1 through holes 8 for discharging chips and cutting oil without clogging.

Although this chip breaker 6 has been described as an example of these cutting blades 2a to 2c, the present invention is not limited to this structure. 9a and 9b are drill belly buttons 1"
A guide pad 9 is located on the periphery of the guide pad 1ζ, which is located in the tangential direction with respect to the cutting blades 2a to 2c.
a is usually called a bearing guide pad, and the cutting reaction force of the cutting blade is mainly received by this guide pad 9a as described later, while the guide pad 9b located on the coaxial extension of the cutting blade 2 is generally used for dimensioning. It is called a guide pad and mainly plays the role of maintaining the hole diameter during drilling, but in the end, the reaction force caused by the cutting action of the cutting blades 2a to 2c is received by the guide pads 9a and 9b and then the drill head 1. It is designed to ensure straightness.

However, in the conventional example, there was a problem in maintaining the straightness of the drill head 1. That is, when these cutting blades of the drill head 1 rotate counterclockwise as shown by the arrow a in FIG. , a reaction force is applied in the opposite direction, that is, in the tangential direction, as shown in FIG. A larger reaction force is locally applied to the hair ring guide butts 9a located tangentially to these cutting blades.

However, the hardness of the work material W is not always uniform over the entire hole wall to be machined. Rather, it is normal that the hardness varies throughout the hole wall, and in this case, the guide pads 9a, 9
When b contacts the hole wall with low hardness, both guide pads 9a,
9b, in particular, a phenomenon occurs in which the hair ring guide pad 9a bites into the hole wall with low hardness, and the drilling direction is corrected to this biting position, and thereafter drilling progresses based on this biting hole wall. As a result, the straightness of the drill head 1 as a whole is reduced.

In this way, in the conventional example, there is a slight problem in the straightness of the drill head I because the direction of action of the cutting reaction force applied to these cutting blades 2a to 2c is on the cutting blade as shown in the line of action. This is because the cutting reaction force is locally applied to the hair ring guide pad 9a among the guide pads 9a and 9b.
Therefore, in order to solve this problem, it is possible to disperse the acting direction of the cutting reaction force so that not only the hair ring guide pad 9a but also the sizing guide pad 9b can receive a considerable amount of the cutting reaction force. Each guide pad 9
a.

Since the cutting reaction force acting on the guide pad 9b, especially the former guide pad 9a, is reduced, the phenomenon of biting into the hole wall is eliminated, and the straightness of the drill head 1 should be improved. Furthermore, the role of maintaining the straightness of the drill head 1 is not only borne by the two guide bars t'' 9a, 9b, but also by the cutting blades 2a to 2c or at least one of them. By doing so, it should be possible to improve the straight-line accuracy.

The object of the present invention is to solve the above problems and ensure the straightness of the drill head 1 without being affected by variations in the hardness of the workpiece.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a deep hole in which an outer cutting blade and an inner cutting blade are attached to a trill head in a radial direction from the rotation axis. In the cutting trill, a part of the cutting edge of at least one of the inner and outer cutting blades described in 1. expands from the radius line on which the cutting edge is located in a tangential direction perpendicular to the radius line or in the rotational direction. The invention adopts a configuration characterized in that it is formed so as to be exposed.

(Function) As shown in FIG.
a and the outer edge 11b on the opposite side are on the radius line P of the drill head 1, and among them, the cutting edge 10 on the most axial center side
The edge 11C on the axis side of the cutting edge portion of C passes through the rotational axis O, and the edge 11C of the cutting edge portion of C passes through the rotational axis O, and the cutting edge portion 11
Almost all of them are formed to bulge in the tangential direction perpendicular to the radius line P or in the rotational direction. When the bulging portion of the cutting edge portion 11 is formed, for example, in a substantially trapezoidal shape when viewed from above, that is, from the axial direction, the inner edge llc on the axial center side with the top of the trapezoid in between is approximately perpendicular to this. A cutting reaction force is applied in the direction C, and a cutting reaction force is applied in the direction d, which corresponds to the above, to the outer edge llb on the opposite side. The cutting reaction force is not concentratedly applied to the ring guide pad 9a, but the reaction force is also applied in a direction close to the other guide pad 9a, so that the cutting reaction force is averaged by both guide pads 9a and 9h. The load will be distributed across the Furthermore, by forming the cutting edge portion 11 into bulging edges lla, llb, and llc in the tangential direction or rotational direction, the bulging edges bite into the workpiece W continuously during the cutting operation, and this biting action causes the cutting blade to 10 is regulated by the biting surface of the workpiece W, and displacement of the cutting blade 10 in the radial direction is reliably prevented. By using both of the above, the biting action of both guide pads 9a and 9b on the drill head 1 into the hole wall is reduced, and the straightness of the guide pad 1 is improved.
You can count two. Note that the above-mentioned action is achieved by providing the above-mentioned bulging edge on at least one cutting blade 10a, 10b, or 10c among these inner and outer cutting blades 10a~], Oc, and forming the above-mentioned bulging edge on the other cutting blade as shown in FIGS. 7a and 7b. It is clear from the above description that this can be achieved even by using the conventional method shown in FIG.

(Example) FIG. 2a and FIG. 2S show an example of the present invention, in which cutting blades 12a to 12c provided on the drill head 1 are shown.
As shown in Fig. 2a, the cutting edge portion 13 is bulged in a substantially triangular shape in plan view, and the bulging edges 13a and 13b facing in two directions are naturally exposed to the blade from two directions as shown by the arrows. A cutting reaction force is applied to both guide pads 9a.
, 9b is intended to prevent one of the guide pads 9a from receiving the cutting reaction force intensively, but rather than this action, the bulging edges 13a and 13b
The restricting action of biting into the workpiece W (shown in FIG. 7a) prevents the displacement of each of the cutting blades 12a to 12c, and therefore the drill head 1, in the radial direction, thereby ensuring its straightness. It is something to do.

Note that by forming the cutting edge portions 13 of each of the cutting blades 12a, 12b, and 12c into bulging edges 13a and 13b that are approximately triangular in plan view, chip breakers 4a and 1.4b are formed along each bulging edge. Also rake surface 15a.

15b naturally faces in two directions. 8 is a discharge port for cutting waste and cutting oil.

3 to 6 show the main parts of other embodiments, that is, the structure of the cutting blade. In FIG. 3, the bulging edge on the axial center side is short and the bulging edge on the circumferential side is long. 4 shows a cutting blade 16 that bulges out from the radial line of the drill head in a tangential direction or rotational direction in a deformed triangular shape when viewed from above. In contrast, FIG. It also shows a cutting blade 17 that bulges out in a deformed triangular shape in plan view.
FIGS. 5 and 6 respectively show cutting blades 18 and 19 having elliptical arc-shaped or circular arc-shaped bulging edges.

(Effects of the Invention) According to the present invention, even if there is variation in the hardness of the workpiece being cut by the cutting blade of the drill head during cutting, the drill head can move straight without being affected by this variation. It is possible to ensure sex.

[Brief explanation of the drawing]

Fig. 1 is a plan view for explaining the configuration and operation of the present invention, Fig. 2a is a plan view of an embodiment of the invention, and Fig. 2 is a front view showing the inside with a portion cut away. 3 to 6 are plan views showing the cutting blade which is the main part of other embodiments of the present invention, and FIGS. 7a and 7 are plan views and partially cutaway front views of conventional examples. be. 1... Drill head, IOa~10c... Cutting blade,
1]. 13...Blade tip, 12a to 12c, 16.17.1
8.19...Cutting blade. Applicant Nippon Yakin Co., Ltd. 0 Figure 1 Figure 2 a Figure 7 O Figure 7 b

Claims (1)

[Claims] In a deep hole cutting drill in which an outer cutting blade and an inner cutting blade are attached to a drill head in a radial direction from the rotation axis, the cutting edge of at least one of the inner and outer cutting blades is A deep hole cutting drill characterized in that a portion of the cutting edge portion is formed to bulge out from the radius line where the cutting edge portion is located in a tangential direction orthogonal to the radius line or in the rotational direction.