JPS60221209A - 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 the cutting part of the drill at the bit. CONSTITUTION:The tip portion 13 of a cutting part 12 provided at the bit 1 of a drill is protruded nearly in the form of a trapezoid. Cutting reaction forces act to protruded edges 13a, 13b, 13c. As a result, one of guide pads 9a, 9b is prevented from receiving the cutting reaction forces concentratedly. The protruded edges 13a, 13b, 13c cut into a workpiece so as to perform a restricting action for keeping the drill bit 1 from being displaced in the radial direction. The straight movement of the drill bit 1 is thus assured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a single-blade drill for cutting and forming deep holes in metal workpieces.

(Prior art) Figures 7a and 7s show conventional examples.
2 is a cylindrical drill head, and 2 is a cutting blade fixed to the thick part of the tip of the drill head by brazing or the like.As shown in FIG. The inner edge 3a of the cutting edge portion 3 always passes through the rotation axis O of the drill head 1, and the inner edge 3a passes through the rotation axis O and moves to the right in the figure. The extending portion does not perform a cutting action, but is commonly formed in manufacturing. Furthermore, as shown in FIG. 7, this cutting blade 2 has a substantially mountain-shaped shape when viewed from the front, and the axial center side with the top thereof sandwiched therebetween is referred to as the above-mentioned inner edge 3a.
The opposite side is referred to as the aucuesoji 3b, and this shape is often used in a drill head consisting of a single cutting blade, which is the object of the present invention, but it is of course not limited to this. Further, a step portion 5 is formed on the rake face 4 of the cutting blade 2 along the cutting edge portion 3, and is shaped like a hole or J when viewed from the side, and this step portion 5 is called a chip breaker. The chip breaker 5 functions to finely divide the chips into pieces at appropriate intervals in the longitudinal direction. Furthermore, a stepped portion 7 is formed on the flank surface 6 of the cutting blade 2, and this is called a chip separator, and the chips are finely divided in the width direction by this chip separator tuff, and due to the synergistic effect of these steps, drill head 1
Chips and cutting oil are discharged smoothly from the hollow interior of the hole 8 for discharging chips and cutting oil without clogging.

This chip breaker 5 and chip separator 7 are the cutting blade 2
Although described as an example, the present invention is not limited to this structure. 9a and 9b are guide pads provided on the periphery of the drill head 1. Of these, the guide pad 9a located tangentially to the cutting blade 2 is usually called a bearing guide pad, and the cutting reaction force of the cutting blade 2 will be described later. The guide pad 9b located on the coaxial extension line of the cutting blade 2 is generally received by the guide pad 9a as shown in FIG. However, in the end, the reaction force due to the cutting action of the cutting blade 2 is transferred to both guide pads 9a,
The straightness of the drill head 1 is ensured while being received by the drill head 9b.

However, in the conventional example, this l.
There was a problem with maintaining straightness. That is, when the cutting blade 2 of the drill head 1 rotates 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 the line of action, and this reaction force is received by both guide pads 9a and 9b that are in contact with the workpiece W. In particular, as described above, Is it tangential to the cutting edge 2? A larger reaction force is locally applied to the hair ring guide path F'9a.

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, the bearing guide pad 9a bites into the hole wall with low hardness, and the drilling direction is corrected to this biting position, and thereafter drilling proceeds based on this biting hole wall. As a result, the straightness of the drill head 1 as a whole is reduced.

In this conventional example, there is a slight problem in the straightness of the drill head 1 because the direction of action of the cutting reaction force applied to the cutting blade 2 is directed toward the cutting blade 2 as shown in the line of action. oriented in the tangential direction, which is why both the guide pads 9
This is because the cutting reaction force is locally applied to the hair ring guide pad 9a among a and 9b. Therefore, in order to solve this problem, the direction of action of the cutting reaction force is distributed, and if only the bearing guide pad 9a is used. If the sizing guide pad 9b is also made to absorb a considerable amount of the cutting reaction force, each guide pad 9a, 9b will be reduced accordingly.

In particular, since the cutting reaction force acting on the former guide pad 9a is reduced, the phenomenon of biting into the hole wall is eliminated to that extent, and it is possible to improve the straightness of the drill head 1. Furthermore, by placing the role of maintaining the straightness of the drill head 1 not only on the guide pads 9a and 9b, but also on the cutting blade 2 itself, it should be possible to further improve the straightness of the drill head 1. .

The object of the present invention is to solve the following 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 cutting drill in which a single cutting blade is attached to a drill head in a radial direction from the rotation axis. In this method, a part of the cutting edge of the cutting blade is formed so as to bulge out from the radius line where the cutting edge is located in a tangential direction perpendicular to the radius line or in the direction of rotation. It is something.

(Function) As shown in FIG. 1, the cutting blade 10 attached to the drill head 1 has an inner edge lla of its cutting edge portion 11 passing through the rotational axis O, and an outer edge between the rotational axis 0 and the outer edge. Almost all of the cutting edge portion 11 is formed so as to bulge out in the tangential direction perpendicular to the radius line P or in the rotational direction from above the radius line P connecting the outermost edge 11b1 of the blade 11b. When the swollen portion of the cutting edge portion 11 is formed, for example, in a substantially triangular shape when viewed from above, that is, from the axial direction, the inner edge lla on the axial center side with the triangular apex sandwiched therebetween is approximately shaped like this. A cutting reaction force in the orthogonal direction C is applied,
On the other hand, a cutting reaction force is applied to the outer edge llb on the opposite side in a direction d corresponding to the above, and in either case, a cutting reaction force is applied locally to the bearing guide pad 9a located in the tangential direction. Instead, the reaction force is applied in the outer direction of the cutting blade 10 and in the direction approaching the other guide pad 9a, and as a result, the cutting reaction force is applied to both guide pads 9a.
, 9b, the load is distributed evenly.

Furthermore, by forming the cutting edge portion 11 into bulging edges lla and llb in the tangential direction or rotational direction, the bulging edges continue to bite into the workpiece W during the cutting operation, and this biting action causes the cutting blade 10 to Displacement of the cutting blade 10 in the radial direction is reliably prevented by being restricted by the biting surface of the workpiece W. Both of the above effects reduce the biting action of the guide pads 9a, 9b of the drill head 1 into the hole wall, thereby making it possible to improve the straightness of the guide pad 1.

(Embodiment) FIGS. 2a and 2s show an embodiment of the present invention, in which the cutting blade 12 provided on the drill head 1 has a cutting edge portion 13 as shown in FIG. 2a in plan view. The bulging edges 13a, 13 are bulged into a substantially trapezoidal shape and face in three directions.
Naturally, cutting reaction forces from three directions are applied to the guide pads 9a and 13c as shown by the arrows.
This is intended to prevent one of the guide pads 9b from receiving the cutting reaction force intensively.
Rather than this action, the cutting blade 12,
Therefore, it is intended to prevent the trill head 1 from being displaced in the radial direction, thereby ensuring its straightness.

Chip breakers 1.4a, 14b are formed along each bulging edge by forming the cutting edge portion 13 of the cutting blade 12 into a substantially trapezoidal bulging top/notch 13a to 13c in plan view.
14C also has rake faces 15 a, 15 b, 15
Naturally, c also faces in three directions. Note that 16 is the flank 17
A chip separator 8 provided at 8 is a discharge port for cutting waste and cutting oil.

Figures 3 to 6 show the main parts of other embodiments, that is, the structure of the cutting blade. In Figure 3, the inner edge side is short and the outer edge side is long, so that it has a deformed triangular shape in plan view. This shows the cutting blade 18 that bulges out from the radial line of the drill head in the tangential direction or rotational direction. In contrast, FIG. 5 and 6 show cutting blades 20 and 21 having elliptical or circular arc-shaped bulging edges, respectively.

(Effects of the Invention) According to the present invention, even if the hardness of the workpiece cut by the cutting blade of the drill head varies during cutting, the straightness of the drill head is hardly affected by this variation. can be ensured.

[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, 10... Cutting blade, 11.13
-...Blade tip, 12.18.19.20.21...Cutting blade. Applicant Nippon Yakin Co., Ltd. 0 Figure 2 0 169b Figure 1 130 3b Snake Figure 2 b 11b + 13 1 10; ) Figure 70 ) Figure 7b

Claims (1)

[Claims] In a deep hole cutting drill in which a cutting blade is attached to a drill head in a radial direction from the rotation axis, a part of the cutting edge of the cutting blade is attached to the drill head from a radius line where the cutting edge is located. A deep hole cutting drill characterized by being formed to bulge in a perpendicular tangential direction or a rotational direction.