JP3222515B2 - Hole cutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manual hole cutter in which a plurality of cutting blades are arranged in a row at the peripheral edge of a cylindrical body.

[0002]

2. Description of the Related Art In a hole cutter of this type, it is necessary to reduce the cutting resistance by smoothly discharging chips generated during the drilling from the portion where the cutting is performed. Has a decisive effect on the cutting performance of the hole cutter.

However, a conventional hole cutter, particularly a hole cutter used for manual drilling, has a so-called flat blade in which the cutting edge extends in a straight line and no step is formed. Therefore, the drilling operation can be performed relatively smoothly in the initial stage of drilling, but since wide chips are cut out from the flat blade, the discharge is not performed smoothly and the cutting resistance is large. For this reason, as the drilling progresses, the cutting resistance increases, and a great deal of manual work is required.

[0004] The present invention has been made in view of the problems existing in such prior art, and an object thereof is to provide a hole cutter which can smoothly discharge chips and has a small cutting resistance. To provide.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a cylindrical body to which rotation about an axis and feed along the axis are provided, and an evenly spaced end edge of the body. Four or more arranged cutting blades, a chip discharging gullet formed on the periphery of the end portion of the body so as to be located between the cutting blades, and the cutting blades each have a rake face having the same angle. The cutting edge is composed of a first cutting edge and a second cutting edge, the cutting edges have the same relief angle, and the first cutting edge is on the rotation direction side. In front, and having an inner cutting edge positioned inside the body, and an outer cutting edge positioned rearward in the rotation direction and outside the body, and the cutting edge of the second cutting edge has an obtuse angle. No, the vertex is near the center <br/> over the body and outside the cutting edge And a vertex portion of the cutting edge of the second cutting edge is formed so as to advance in the feed direction with respect to a cutting edge of the first cutting edge, and both end portions of the vertex portion are formed by a cutting edge of the first cutting edge. And that the body is retracted in the feed direction.

[0006]

According to the hole cutter of the present invention, when rotation about the axis and feed along the axis are given to the cylindrical body, the cutting blade disposed at the end of the body performs piercing.
Chips generated during the perforation cutting are discharged from a gullet located between the cutting blades. More specifically, in drilling, the following operation is continued. That is, the workpiece is alternately and continuously cut by the two cutting edges. At this time, the obtuse vertex of the cutting edge of the second cutting edge is located at the center of the cutting edge in the inward and outward directions of the body.
Since it is near, the apex goes around the center of the bottom of the groove to be machined. On the other hand, both ends of the apex portion are not involved in cutting and chips are not cut out. Next, by the cutting edge of the first cutting blade,
Cutting is performed. In this case, the portions to be cut are portions corresponding to both end portions of the cutting edge of the second cutting blade. Since the cutting edges of the first cutting blades are shifted back and forth in the rotation direction, the chips are also discharged from the shifted positions and do not entangle with each other.

[0007]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. As shown in FIG. 1, a body 1 has a cylindrical shape, and a shank 2 for attaching the hole cutter to a chuck (not shown) is integrally provided at one end thereof.

As shown in FIGS. 1 and 2, first and second cutting edges 3 and 4 are embedded and fixed to the periphery of the other end of the body 1, and these cutting edges 3 and 4 are alternately arranged at equal intervals. Are mixed and arranged. A plurality of discharge gullets 5 are formed on the periphery of the end of the body 1 at the front of the first and second cutting edges 3 and 4 in the rotation direction. The plurality of grooves 6 are formed along the outer peripheral surface of the end of the body 1 so as to correspond to the respective discharge gullets 5. The discharge gullet 5 and the groove 6 have cutting edges 3 and 4 respectively.
It is for discharging the chips shaved in the above. The discharge gullet 5 is oblique, and in this embodiment, the angle θ4 is 3 ° with respect to a plane orthogonal to the axis 18 of the cutter.
0 degrees.

At the center of the body 1, a stopper 7 is integrally formed on the circumference thereof.
And the work 19 are in contact with each other to restrict the movement of the cutter.
As shown in FIG. 2, the first and second cutting edges 3, 4 have rake faces 8a, 8b having the same inclination angle, respectively. In this embodiment, the angle θ1 of these rake faces 8a and 8b is 2
0 degrees. Also, the clearance angle θ2 of the first and second cutting blades 3, 4
Is 9 degrees.

The non-cut surface 9 is formed on the rake face 8a of the first cutting edge 3.
Are formed along the direction of the axis 18. For this reason, the cutting edge 10 of the first cutting edge 3 has an inner cutting edge 11 located in front of the body 1 in the rotation direction and inside the body 1 and an outer cutting edge 11 located in the back in the rotation direction and outside the body 1. Cutting edge 1
2 are formed so as to be discontinuous via the non-cutting surface 9. As shown in FIG. 6, the flank 13 formed at the lower end of the first cutting edge 3 and having the clearance angle of θ2.
Therefore, the inner cutting edge 11 projects in the direction of the axis 18 by α from the outer cutting edge 12. Also, the width of the inner cutting edge 11 and the outer cutting edge 12 are formed to be the same. First cutting edge 3
The inner and outer cutting edges 11, 12 are inclined with respect to a plane orthogonal to the axis 18, and the angle θ3 is 4 degrees.

As shown in FIG. 7, the cutting edge 1 of the second cutting blade 4
4 has an obtuse angle, and the vertices are inside and outside the body 1 of the cutting edge 14.
Near the center in the direction . A ridgeline 15 extends from the vertex of the cutting edge 14 at its lower end, and an inner flank 16 and an outer flank 17 divided by the ridgeline 15 are formed. The cutting edge angle θ6 of the second cutting blade 4 is 140 degrees. The first and second cutting blades 3 and 4 are slanted on both side surfaces so as to be thinner toward the upper side, and the angle θ5 is 4 degrees.

As is apparent from FIG. 8, both ends of the cutting edge 10 of the first cutting edge 3 are connected to the cutting edge 14 of the second cutting edge 4.
The cutting edge 14 of the second cutting edge 4 projects more in the feed direction than the cutting edge 10 of the first cutting edge 3.

Next, the cutting action of the hole cutter configured as described above will be described with reference to FIG. The rotation about the axis 18 and the feed along the axis 18 are manually applied to the body 1. These first and second cutting edges 3, 4
The work 19 is cut by the
An annular machined groove 20 is formed in 9, resulting in a perforation.

As shown in FIG. 8, in the case of cutting with the second cutting edge 4, both end portions of the cutting edge 14 of the second cutting edge 4 are retracted in the feed direction from the cutting edge 10 of the first cutting edge 3. And does not participate in cutting, and chips are not removed. The vertex of the cutting edge 14 of the second cutting edge 4 corresponds to the cutting edge 10 of the first cutting edge 3.
Since it is more advanced in the feed direction, a single narrow chip corresponding to the apex portion is cut out. Next, cutting by the feed amount is performed by the cutting edge 10 of the first cutting blade 3. In this case, the central portion of the cutting edge 10 of the first cutting edge 3 does not participate in cutting. Blade edge 10 of the first cutting edge 3
The portions cut by are the portions corresponding to both end portions of the cutting edge 14 of the second cutting blade 4, that is, the side of the axis 18 of the inner cutting edge 11 and the outer portion of the outer cutting edge 12.

Thus, the cutting edge 10 of the first cutting blade 3
The three cutting chips cut by the inner cutting edge 11 on the side of the axis 18, the outer portion of the outer cutting edge 12, and the apex of the cutting edge 14 of the second cutting edge 4 are cut out. Therefore, the chips to be cut at this time are thick chips having a small width.

Although cutting is performed as described above, since the cutting motion of the two cutting edges 3 and 4 is a rotational motion about the axis 18 of the body 1, the cutting speed of the inner and outer cutting edges is different, and the cutting is performed from the inside. Emitted chips come out at a slower rate than outer chips. For this reason, it is difficult to get entangled by the speed difference.
In addition, as for the cutting edge 10 of the first cutting blade 3, since the inner cutting edge 11 is advanced in the rotation direction with respect to the outer cutting edge 12, the cutting position of the chips is also shifted back and forth.
Due to the shift of the cutting position of the chips, the chips are hardly entangled with each other. Therefore, the chips are discharged very smoothly. As described above, since the narrow chips are smoothly discharged without entanglement with each other, the cutting resistance can be reduced, and the operation can be efficiently and easily performed even in the case of manual drilling. The cutting blades 3 and 4 do not cut over the entire width, but perform cutting only partially, so that the cutting force is small, which can contribute to the easiness of work.

[0017]

[Other Embodiments] The present invention is not limited to the configuration of the above embodiment, but can be embodied in the following modified examples.

(1) The total number of the cutting blades 3 and 4 is four or more. (2) Each rake face 8 in the first and second cutting edges 3 and 4
a, 8b, angles θ1 to θ6 such as clearance angles are changed as necessary.

[0019]

As described in detail above, according to the present invention, an excellent effect is obtained that the chips of the hole cutter can be satisfactorily discharged and the drilling operation can be performed extremely efficiently.

[Brief description of the drawings]

1 is a positive plane view showing an embodiment of embodying hole cutter of the present invention.

FIG. 2 is a front view showing a cutting blade of the hole cutter.

FIG. 3 is a front view showing a first cutting blade of the hole cutter.

FIG. 4 is a bottom view showing the first cutting blade of the hole cutter.

FIG. 5 is a front view showing a second cutting blade of the hole cutter.

FIG. 6 is a sectional view showing a first cutting blade of the hole cutter.

FIG. 7 is a sectional view showing a second cutting blade of the hole cutter.

FIG. 8 is a sectional view showing the cutting action of the hole cutter.

[Explanation of symbols]

1 body, 3 first cutting edge, 4 second cutting edge, 5 gallet, 8a, 8b rake face, 10, cutting edge, 11 inner cutting edge, 12 outer cutting edge, 14 cutting edge, 18 axes.

Claims (1)

(57) [Claims] A cylindrical body (1) provided with rotation about an axis (18) and feed along the axis (18).
And four or more cutting blades (3, 4) arranged at equal intervals around the edge of the body (1), and the body (1) is positioned between the cutting blades (3, 4). ) And the cutting edge (3, 4) formed on the periphery of the end of the cutting edge (5) and the rake face (8a,
8b), the cutting edge (3, 4) is constituted by a first cutting edge (3) and a second cutting edge (4), and the cutting edge (3, 4) Have the same relief angle, and the first cutting edge (3) is located on the front side in the rotation direction, and on the inner cutting edge (11) located inside the body (1), and on the rear side in the rotation direction. And an outer cutting edge (12) located outside the body (1), and the cutting edge (14) of the second cutting blade (4) forms an obtuse angle,
The apex is located inside and outside the body (1) of the cutting edge (14).
And the vertex portion of the cutting edge (14) of the second cutting edge (4) is formed to advance in the feed direction with respect to the cutting edge (10) of the first cutting edge (3). A hole cutter characterized in that both end portions of the apex portion are retreated in the feed direction of the body (1) from the cutting edge (10) of the first cutting edge (3).