JPS599776Y2 - Throw-away drilling tool - Google Patents

Description

[Detailed description of the invention] This invention has one cutting edge that is continuous from the rotation center side to the outer periphery in the rotation locus at the tip of the tool body.
Alternatively, the present invention relates to a single-blade throw-away type drilling tool in which two or more cutting tips are exchangeably attached by a clamp member, and the tool body is cut down in the axial direction to perform drilling processing (so-called blank hole processing).

A typical example of this type of single-blade indexable drilling tool is the single-blade indexable drill. introduce.

The drill shown in FIGS. 1 and 2 has a structure in which two throw-away tips 1 and 2 with rounded noses at the four corners are attached to the tip of a tool body 4 with a clamp member 3 such as a screw. These two throwaway tips 1
, 2 are arranged so that each cutting edge ridge 1a, 2a constitutes one cutting edge in the rotation locus, and one of the rounded noses of the tip 1 located inward in the radial direction is located at its virtual tip. is set so that it is located on the rotation center O.

The drill shown in FIGS. 3 and 4 has a parallelogram tip 5 attached to the tip of the tool body 4 by a clamp member 3, and the cutting edge 5b of the parallelogram tip 5 rotates. It is arranged so as to include the center O and extend in the radial direction.

As can be seen from these, in any conventional indexable drill, the cutting edge ridge la, 5
A is configured so that a part thereof includes the center of rotation O, which requires high index accuracy, and requires extremely high accuracy of the cutting edges 1 and 5 and processing accuracy of the tool body 4. was.

In particular, in the drills shown in Figs. 1 and 2, when providing a radial rake or an axial rake, more complicated dimensional control is required to position a part of the cutting edge 1a on the rotation center O. This results in great difficulties in processing.

Therefore, even when a large rake angle is required depending on the type of workpiece material, it is not easy to obtain a large rake angle, making it difficult to obtain sufficient cutting performance.

In addition to the above-mentioned problems regarding the machining accuracy of the cutting tip and the tool body, in conventional single-flute indexable drills, the cutting edge is located at the rotation center O, so Various disadvantages were unavoidable, such as a large thrust load due to insufficient relief angle at the center O section, and (1) easy damage to the cutting edge due to welding and peeling caused by insufficient cutting speed at the rotation center O section.

This point is the same for general solid type drills, and the contents are detailed in, for example, "Cutting and Grinding Processing, Volume 1 JP 332-334, written by Eiji Usui, Kyoritsu Shuppan, etc." By the way.

This idea was made in consideration of the above points, and there are various disadvantages caused by having the cutting edge at the center of rotation, and the fact that both the tool body and the cutting edge tip require high machining accuracy, making manufacturing difficult and costly. The purpose of the present invention is to provide a conventional single-blade throw-away type drilling tool that can effectively solve both of the problems of height.

Hereinafter, the content of this invention will be explained in detail with reference to the attached FIGS. 5 to 12.

First, to describe the features of this invention, the first feature of this invention is that the cutting edge tip adjacent to the center of rotation (hereinafter sometimes referred to as the inner tip).

), the inner edge of the cutting edge is also (0.1mm) from the center of rotation.
%≦1.25 mm).

Since the inner edge is separated from the center of rotation in this way, there is no cutting edge at the center of rotation.

Therefore, it is possible to eliminate the various disadvantages described above that occur when a cutting edge is present at the center of rotation.

Note that if there is no cutting blade at the center of rotation, a cylindrical core that remains uncut at the center of rotation would have a certain length.

However, when the inner edge of the cutting edge is set to the above value, the core is pressed and bent by the inner edge, and is repeatedly bent as the inner edge rotates.

This repeated bending causes it to break off from its base end.

Therefore, no core remains.

By the way, by moving the inner edge of the cutting edge away from the center of rotation, the thrust load acting on it can be reduced and the cutting speed can be increased. Damage to the cutting edge can be largely prevented.

However, when looking at the same drill, even if the inner edge is moved away from the center of rotation, the inner edge portion is more likely to be damaged than the outer peripheral side portion.

Moreover, since the inner edge is used to press and bend the core, it is desired that the inner edge has high strength.

Therefore, in this invention, the part of the rake face of the inner insert near the center of rotation is shaped into a single or multi-step convex curved surface or an arc-shaped convex curved surface, and the center of rotation of the cutting edge of the inner insert is The second and third features are that the portions near the tool body are shaped so as to move from the outer circumferential side to the inner edge and from the leading end to the rear end of the tool body, respectively.

When shaped in this way, it is possible to increase the angle between the rake face and the side surface of the chip near the inner edge, the angle between the cutting edge and the side surface, etc., and thereby the inner edge portion This allows the strength to be improved.

Next, in order to clarify such characteristics, examples of this invention will be specifically described.

[First Embodiment] (See Figures 5 and 6) The drill of this first embodiment is equipped with two parallelogram-shaped flat tips 6 and 7 as throw-away tips, and each cutting edge tip has two parallelogram-shaped flat tips 6 and 7. 6 and 7 are attached to the tip of the tool body 4 by clamp members 3 such as screws (this attachment method itself is the same as the conventional one, and screw pieces or bolts can also be used as the clamp members 3). You can do that).

Of these two cutting blade tips 6 and 7, the tip 6 located outward in the radial direction has the same arrangement as the tip 2 in FIG. 1, but the other tip located inward in the radial direction Chip 7 has a different shape and arrangement from the corresponding chip 1 in FIG.

That is, as shown in FIG. 7, the cutting edge tip 7 here is entirely point-symmetrical in shape and has a rake face 8 and four side faces 9, 10, 11, and 12.

The two side faces 9, 11 facing each other are perpendicular to the rake face 8, and the other two side faces 10, 12 are shaped to intersect the rake face 8 at an acute angle.

A corner formed by the rake face 8, side face 9, and side face 10 is cut off from the rake face 8 toward the side face 10, and a single-stage convex face 13 is formed there.

Note that convex surfaces 13 are also formed at the corners formed by the rake surface 8, side surfaces 11, and 12.

In addition, the rake face 8, the convex face 13 and the side face 10 (12)
A cutting edge 7a is formed on the ridge.

The cutting edge tip 7 configured in this way has its side surface 9 parallel to the rotation center O, and the cutting edge 7a and the side surface 9.
% from the center of rotation O
They are attached to the tool body 4 with a distance of (0.1 mm≦%≦1.25 mm).

When installed in this way, the convex surface 13 of the cutting edge 7a
Since the side surface 10 intersects with the rake surface 8 at an acute angle, the tip of the tool body 4 moves from the outer circumferential side toward the inner edge 7b. It will slope from the side toward the rear end.

Therefore, in the drill configured in this way, although the inner edge 7b is separated from the rotation center O, it is no longer necessary to position a part of the cutting edge at the rotation center, and the tool body 4 and the cutting edge are separated from each other. There is no need to increase the machining accuracy of the blade tip 7 as in the conventional case, and therefore the tool can be manufactured at low cost.

Further, since the angle between the convex surface 13 and the side surface 9 is larger than the angle between the rake surface 8 and the side surface 9, the strength of the inner edge 7b portion can be improved.

Moreover, since the cutting edge 7a is shaped so as to go from the tip side to the rear end side as it goes from the outer circumferential side to the inner edge 7b, the angle between the cutting edge 7a and the side surface 9 becomes larger. ,
This makes it possible to further improve the strength of the inner edge 7b portion.

In addition, when drilling with the above-mentioned drill, since there is no cutting edge at the center of rotation O, the thrust load can be reduced, and welding can be prevented to prevent chipping of the cutting edge. I can do it.

Moreover, the core that should extend to the center of rotation O has an inner edge 7b.
broken by.

Then, the broken core is discharged to the outside from either of the chip discharge grooves 15 and 16.

At this time, since this drill has a single blade, that is, only one cutting edge tip 7 is disposed near the rotation center O, the tip surface of the tool body 4 is more A sufficiently large space is available in front of the chip so that the broken core can be immediately discharged into the chip evacuation groove 15,16.

In addition, by making the portion of the rake face near the rotation center O a convex surface 13, (a) the length of the cutting edge 7a becomes longer;
The load per unit length of the cutting edge is reduced. (b) Cutting edge breakage and abnormal wear are less likely to occur, allowing high feed rates.
C) It causes slippage that shears chips, making it difficult to form welds, (d) It becomes difficult to form a sharp cutting edge,
Chipping of the cutting edge is less likely to occur. (e) Chip processing and discharge are even better, and hole machining accuracy is improved.
Benefits such as:

[Second Embodiment] (See Figures 8 and 9) In the drill of this second embodiment, one cutting edge extending from the rotation center O side to the outer periphery is constituted by one cutting edge tip 7. be.

The cutting tip used here is the same as the radially inner tip 7 in the first embodiment, and also in this second embodiment, the inner edge 7b of the cutting tip 7 and the center of rotation O are a little apart. and the distance % between them is set in the same way as above.

Note that in both this second embodiment and the first embodiment, the chip discharge groove 14. 15 is a straight groove along the axial direction of the tool body 4, and there is no rake angle in the axial direction of the cutting edge tip, but it goes without saying that this may be a helical groove or a rake angle may be provided.

Further, the round hole 16 in the figure indicates an oil hole.

[Third Embodiment] (See FIG. 10) The drill shown in FIG.
A cylindrical convex curved surface 17 is provided at the side corner.

In this way, when the convex curved surface 17 is provided in place of the convex surface 13, the effect of the convex surface 13 can be further exhibited.

Note that when a multi-stage convex surface is used instead of the single-stage convex surface 13, the effect is intermediate between that of the single-stage convex surface 13 and the convex curved surface 17.

Although the above description has been made regarding a normal throw-away type drill, this invention is not limited to that, and of course can be applied to a gun drill for deep hole drilling, a BTA tool, etc. as long as it is a throw-away type. .

As described above, in the single-flute indexable drilling tool of this invention, the inner edge of the cutting edge of each cutting edge is separated from the center of rotation of the tool body relative to the workpiece, In other words, since there is no cutting edge in the center, it is possible to eliminate the various disadvantages mentioned above when the cutting edge is in the center of rotation. Since it is not necessary to position a part of the tool body at the center of rotation, the processing accuracy of the tool body and the cutting edge tip is not required to be as high as in the past, and therefore the tool itself can be manufactured at low cost.

In addition, the part of the rake face near the rotation center is formed into a convex curved surface or a cylindrical convex curved surface in single or multiple stages, and the part of the cutting edge near the rotation center is shaped from the outer circumferential side toward the inner edge. Therefore, since the shape extends from the leading end to the rear end of the tool body, the strength of the portion near the inner edge can be improved and damage to that portion can be further prevented.

Furthermore, by making the portion of the rake face near the rotation center a convex surface or a convex curved surface, (a) the length of the cutting edge becomes longer and the load per unit length of the cutting edge is reduced; (b) the cutting edge chipping and abnormal wear are less likely to occur, making high feed possible; (C) slipping that shears chips occurs and welding is less likely to occur; (d) the structured cutting edge is less likely to develop; It is also possible to obtain advantages such as chipping of the cutting edge becomes less likely to occur, (e) processing and discharge of chips becomes even better, and hole machining accuracy improves.

[Brief Description of the Drawings] Figures 1 and 2 show an example of a conventional single-flute indexable drill, with Figure 1 being a bottom view, Figure 2 being a front view, Figures 3 and 4 being The figures show other examples of the prior art, in which Fig. 3 is a bottom view, Fig. 4 is a front view, Figs. The figure is a front view, and Figure 7 is a partially omitted perspective view of the cutting tip used there.
8 and 9 show a second embodiment of this invention, FIG. 8 is a bottom view, FIG. 9 is a front view, and FIG. 10 is a bottom view of a third embodiment of this invention. 3... Clamp member, 4... Tool body, 6, 7... Cutting blade tip, 7a... Cutting edge ridge, 7b... - Inner edge, 8... rake face, 13... convex surface, 17... convex curved surface.

Claims (1)

[Scope of utility model registration request] One or more cutting edges forming one continuous cutting edge from the rotation center side of the tool body to the outer periphery of the tool in the rotation locus are attached to the tip of the tool body so as to be replaceable by a clamp member, and the tool In a single-blade indexable drilling tool that performs drilling by cutting down in the axial direction of the main body, the inner edge of the cutting edge of the cutting edge adjacent to the center of rotation is % (0) from the center of rotation. .1mm
≦Dynamic≦1.25ri+m), and the portion of the rake face of the cutting tip adjacent to the rotation center near the rotation center is formed into a convex surface bent in a single or multiple stages or a convex curved surface in the shape of an arc. The cutting edge of the cutting edge adjacent to the rotation center is shaped so that a portion of the cutting edge of the cutting edge adjacent to the rotation center is shaped so as to move from the tip side to the rear end side of the tool body as it goes from the outer circumferential side to the inner edge. A single-blade throw-away type drilling tool.