JP2001150219A - Indexable rotary cutting tools - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary cutting tool capable of performing not only planing work but also back facing work making a bearing surface vertical to a rotary shaft with no work of a prepared hole by the single rotary cutting tool. SOLUTION: A bottom cutting edge 27 is formed by two throwaway chips 21, an angle θ3 formed by the bottom cutting edge 27 and a rotary shaft J is 90 degrees, two bottom cutting edges 27t are extended along one plane vertical to the rotary shaft J. One bottom cutting edge 27 is extended to also an opposite side as viewed from a tip end surface side beyond its center. Accordingly, even in the case back facing work is applied with no prepared hole, un- worked part is prevented from being generated in the center of a back facing surface of a workpiece.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away rotary cutting tool such as an end mill or a milling cutter, and more particularly, to a plate-shaped square throw-away tip mounted on a tip mounting seat formed in a concave portion at the tip of a holder. The present invention relates to a throw-away rotary cutting tool having a fixed (clamped) tip (hereinafter, simply referred to as a tip).

[0002]

2. Description of the Related Art FIG. 9 shows a rotary cutting tool of this kind (hereinafter referred to as "rotary cutting tool").
This is an example of a cutting tool or simply a tool (1), in which the outer peripheral cutting edge 29 and the bottom cutting edge 27 of the fixed chip 21 are responsible for cutting. And
Among the cutting edges of such a rotary cutting tool 1, a bottom cutting edge 2
Generally, 7 is fixed at an end face side (lower side in the figure) of the tool so as to be inclined so as to be reduced toward the center of the rotation axis J. This inclination angle, that is, the bottom cutting edge angle θ3 formed by the rotation axis J and the bottom cutting edge 27 is usually set to 80 to 87 degrees. Therefore, the rotation axis J such as spot facing with this tool 1
When the punching process of feeding the tool in the axial direction is performed, the seat surface processed by the bottom cutting edge 27 has a shape in which a portion closer to the center is raised. This is because if the bottom cutting edge angle θ3 between the bottom cutting edge 27 and the rotation axis J is vertical, the work material (workpiece) such as planing or grooving is traversed in a direction perpendicular to the rotation axis J. This is because the bottom cutting edge 27 constantly rubs the machined surface in the working to be fed, and is liable to be worn and easily chipped.

[0003] In addition, since the bottom cutting edge of this kind of rotary cutting tool is usually present only in a portion near the outer periphery in the front surface (tip surface) of the tool, when it is used for spot facing or drilling, After drilling a pilot hole in advance, it will be processed. On the other hand, the rotary cutting tool used for this type of counterbore machining is designed to secure the stability of the head of the bolt seated on the counterbore surface after machining. Angle) of 90 degrees is used so that a right angle of the bearing surface with respect to the axis of a hole such as a bolt hole is obtained.

[0004]

As described above, in the conventional rotary cutting tool, horizontal feed processing such as planing and grooving is performed in the direction perpendicular to the rotary shaft, and vertical feed is performed in the rotary axis direction. Nothing could be used for counterbore machining, and different tools were used. Therefore, if planing and spot facing are required on the same workpiece, at least 2
Various types of rotary cutting tools were prepared, and they had to be replaced depending on the processing. In addition, the working efficiency is extremely poor because it is necessary to pre-drill a pilot hole in the spot facing portion.

According to the present inventor, in a work material made of a relatively soft metal such as aluminum or copper instead of a steel material, or a nonmetal such as carbon or resin, the bottom cutting edge is perpendicular to the rotation axis. It has been found that even if planing and grooving (hereinafter, also referred to as transverse feed processing) are performed using such a material, the problem of abrasion hardly occurs. Therefore, if there is a tool that can be used for counterboring without preparing a hole in the same work material made of such a material as well as traversing, there is no need for a single tool, and there is no need to replace it. Improve dramatically.

[0006] The present invention has been made in view of such problems in the conventional rotary cutting tool.
It is an object of the present invention to provide a rotary cutting tool that can perform not only planing but also counterboring in which a bearing surface is perpendicular to a rotation axis without preparing a hole with one rotary cutting tool.

[0007]

According to the present invention, there is provided a rotary cutting tool to which one or a plurality of indexable inserts are fixed, wherein a bottom cutting edge formed by the one or more indexable inserts is provided. Extends along a plane perpendicular to the rotation axis, and when counterboring without a pilot hole, at least one of the bottom cutting edges forms an unprocessed portion at the center of the counterbore surface of the work material. It is characterized by having a length that does not occur.

According to the rotary cutting tool of the present invention, not only flat cutting by lateral feed but also counterboring of a seat surface perpendicular to the rotary shaft without a pilot hole can be performed. Therefore, these two
In the machining of a work material requiring two machining forms, one tool having an outer peripheral cutting edge that matches the diameter of the counterbore may be prepared. In the above means, it is preferable that the bottom cutting edge of the throw-away tip extends along a straight line passing through the rotation axis. Further, in the present invention, “perpendicular to the rotation axis” means that the bottom cutting edge angle θ3 in FIG. 2 is in the range of 89 to 90 degrees.

In the above means, it is preferable that the indexable insert has a bottom cutting edge made of an ultra-high pressure sintered body which is a material different from the insert body. Even if the bottom cutting edge is made of a normal chip material such as cemented carbide, high speed steel or cermet, in a relatively soft metal such as aluminum or copper, or in a work material made of a nonmetal such as carbon or resin, Even if planing or grooving, the problem of wear hardly occurs. However, if the bottom cutting edge is formed of an ultra-high pressure sintered body as described above, it has high wear resistance, and is suitable for processing difficult-to-cut materials, and its life can be extended.

[0010] The ultra-high pressure sintered body may be one containing diamond as a main component (diamond sintered body) depending on the work material,
What is necessary is just to select from what has cubic boron nitride as a main component (it is also hereafter called CBN sintered compact).

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
An embodiment of the present invention will be described in detail. In the drawing, reference numeral 1 denotes a throw-away rotary cutting tool of the present example, which includes a holder 2 and a later-described insert 21
Is mainly configured as follows. Holder 2
A holder tip (2b) expanded coaxially (concentrically) to a large diameter at a position near the tip of a holder shaft (shank) 2a having a substantially circular axis shape.
It has. The holder tip 2 b has two recesses (pockets) 4, 4 cut out in a substantially L-shape when viewed from the tip end face 3 on the blade tip side, and is substantially point-symmetric with respect to the rotation axis (axis) J of the holder 2. Are prepared. And the holder 2 of each recess 4
A tip mounting seat 5 is provided at a position close to the front end surface 3 of the first embodiment. In the present embodiment, the two chips 21 are fixed by a screw-on (screw) method so as to form two blades.
And the like have the same configuration except that the size, such as the length of the bottom cutting edge, is slightly different. Therefore, in the following description, only one of them will be described except for the difference.

The chip mounting seat 5 has a substantially triangular and flat seating surface (bottom surface) 6 for restraining a lower surface 22 of a substantially triangular chip 21 having a plate shape, and two wall surfaces 7 and 8 rising from the periphery of the seating surface 6. Consists of However, in the present embodiment, the seating surface 6 is provided to be inclined with respect to the rotation axis J so as to form an axial rake of, for example, 6 degrees (see FIG. 7). Angle θ1 of the intersection of 7 and 8
Is 60 degrees, and an arc-shaped relief (vacant space) 6a is provided at the intersection. The angle θ2 between the axis J of the holder 2 and the wall surface 7 near the coaxial line J when viewed from above the seating surface 6 is set to, for example, 30 degrees.
In this example, the chip 21 to be mounted is of a negative type, and the wall surfaces 7 and 8 are formed so as to intersect the seat surface 6 at right angles. A screw hole 9 for fixing the chip is provided substantially in the center of the seating surface 6 of the chip mounting seat 5 so as to penetrate therethrough.
The tip 21 is formed to be screwed. In FIG. 2, the chip mounting seat 5 and the chip 21 on the right side are large.

The chip 21 has two side surfaces 23, 2
4 are formed so as to intersect at 60 degrees as viewed from the rake face side, and as viewed from the rake face 28 side, the flank along the side surface 23 and the bottom cutting edge 27 are also formed so as to intersect at 60 degrees. . Since the angle θ2 between the axis J of the holder 2 and the wall surface 7 is formed to be 30 degrees, the two side surfaces 23 and 24 abut against the wall surfaces 7 and 8 of the chip mounting seat 5 (restriction). ), The angle (bottom cutting edge angle) θ3 between the axis J and the bottom cutting edge 27 of the tip 21 is 9
It is formed to be 0 degrees. The portions of both sides 23 and 24 of the chip near the bottom cutting edge 27 are cut substantially parallel to the axis J when viewed from the rake face 28 side, and the outer peripheral cutting edges 29 are configured to be parallel to the rotation axis J, respectively. Have been.

In this embodiment thus formed, the above-described substantially triangular plate-shaped chip 21 (see FIGS. 1 and 6) is seated on the seat surface 6 of the chip mounting seat 5 of the holder 2.
The two side surfaces 23 and 24 are connected to the wall surfaces 7 and 8 of the chip mounting seat 5.
, And the clamp screw 31 is passed through the through hole 26 and screwed into the screw hole 9, so that the tip 21 makes an angle θ3 between the axis J and the bottom cutting edge 27 of the tip 21 to the tip mounting seat 5 by 90 degrees. Fixed as

In the present embodiment, the main body (base body) 20 of the chip 21 is made of a cemented carbide, and
Numeral 7 is a sintered body mainly composed of diamond. That is, the bottom cutting edge 27 is
In this embodiment, after forming as a composite (chip) integrally sintered in two layers with the cemented carbide sintered body 27b, the cemented carbide sintered body is formed in the recess 25 provided in the chip body 20. It is fixed by brazing via a link 27b (see FIG. 8).

In this embodiment, the bottom cutting edge 27 is formed along a straight line passing through the rotation axis J when viewed from the front end face (front) 3 so that the radial rake is at 0 degree.
It is provided so as to exist on one plane perpendicular to the rotation axis J. Then, one tip (right side in FIG. 2) 21 is formed larger than the other tip 21, and the bottom cutting edge 27 of the one tip 21 is arranged to extend somewhat beyond the rotation axis J to the opposite side ( 2 and 3). In this way, even if a punching operation such as spot facing is performed without a prepared hole, an unprocessed portion is not generated at the center position of the rotation axis J.

Thus, in such a rotary cutting tool 1, in the processing of the specific work material, the flat cutting can be performed by performing the transverse feed processing. At this time, the bottom cutting edge 27 rubs the machined surface. In the present embodiment, the bottom cutting edge 27 is made of a sintered diamond and is suitable for cutting aluminum, for example. Even when the same work material made of such a material is counterbored, the rotary shaft portion is cut by the long bottom cutting edge 27, so that the work can be performed without the need for a pilot hole. Furthermore, the bearing surface of the counterbore hole thus formed is flat. As described above, according to the rotary cutting tool 1 of the present embodiment, a single tool can perform counterbore machining in addition to planing without any problem. Therefore, the diameter of the outer peripheral cutting edge is set as a rotary cutting tool that matches the hole diameter of the counterbore. Thereby, extremely efficient processing can be performed on the same work material that requires planing and spot facing.

In the above embodiment, the tip body 20 is made of a cemented carbide and the bottom cutting edge 27 is made of a diamond sintered body.
It is suitable for processing a work material whose work material is made of a relatively soft metal such as aluminum or copper, or a nonmetal such as carbon or resin. When the work material is of high hardness such as hardened steel or chilled cast iron, the bottom cutting edge 27 is preferably made of a CBN sintered body. That is, the bottom cutting edge may be a normal chip material such as a cemented carbide, ceramic, or cermet, depending on the work material, but may be an ultra-high pressure sintered body according to the work material.

In order to extend the life of the cutting edge, titanium nitride (TiN), titanium carbonitride (TiCN), titanium aluminum nitride (TiAlN), or the like is provided on the flank or rake face or both surfaces of the cutting edge regardless of the material. May be applied.

In the above embodiment, the axial rake is 6
Although the embodiment is embodied in the case where the radial rake is 0 degrees, these angles can be embodied as appropriate.

In the above-described embodiment, the case where the tip is embodied in a negative type tool has been described. However, the tool of the present invention can naturally be embodied as having a positive type tip fixed. Further, although the chip is illustrated as having a substantially triangular shape, the present invention is not limited to such a chip shape. That is, 1
Alternatively, when a bottom cutting edge formed by a plurality of throw-away tips extends along a plane perpendicular to the rotation axis, and at the time of counterboring without a prepared hole, at least one of the bottom cutting edges forms a work material. It is sufficient that the center of the spot facing surface has a length that does not generate an unprocessed portion.

Further, in the above-described embodiment, a case where the present invention is embodied in a two-flute milling cutter is exemplified. However, the cutting tool of the present invention can be applied to a single-flute mill such as a boring bar in the same manner. It can also be applied to a milling cutter having a large number of blades. That is, the present invention can be embodied by appropriately changing the design of an end mill, a milling cutter or a drill similar to these without departing from the gist of the present invention, regardless of the number of blades or the type of the rotary cutting tool. In the case of a single blade, the bottom cutting edge of the tip itself is set to a length that does not generate an unprocessed portion at the center of the counterbore surface of the work material when counterboring without a prepared hole. Will be.

[0023]

As is clear from the above description, according to the indexable rotary cutting tool of the present invention, the rotating surface can be rotated by a single rotary cutting tool without not only flat cutting but also pilot hole drilling. It can also be counterbored to be vertical.

[Brief description of the drawings]

FIG. 1 is a partially exploded perspective view of one embodiment of a main part of a throw-away rotary cutting tool according to the present invention, as viewed from a distal end side.

FIG. 2 is an enlarged side view of the cutting tool of FIG. 1 viewed from a throw-away insert having a long bottom cutting edge.

FIG. 3 is an enlarged side view of the cutting tool of FIG. 1 as viewed from a throw-away insert having a short bottom cutting edge.

FIG. 4 is a sectional view taken along line AA in FIGS. 2 and 3;

FIG. 5 is a sectional view taken along line BB in FIGS. 2 and 3;

FIG. 6 is a view of the cutting tool of FIG. 1 as viewed from the front (front end surface) side.

FIG. 7 is a right side view of FIG. 2;

FIG. 8 is an enlarged perspective view of the throw-away tip.

FIG. 9 is a side view illustrating a main part of a conventional cutting tool.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Throw-away rotary cutting tool 2 Holder 2a Holder shaft 3 Holder tip surface 4 Depression of holder tip 5 Chip mounting seat 6 Chip mounting seat surface 7, 8 Wall surface around chip mounting seat 9 Screw hole in seat surface 20 Tip body 21 Throw-away tip 23, 24 Side face of throw-away tip 27 Bottom cutting edge 27a Ultra-high pressure sintered body (diamond sintered body) 28 Rake face of chip 29 Outer peripheral cutting edge θ3 Cutting angle J Rotation axis (axis)

Claims (5)

[Claims] 1. A throw-away rotary cutting tool to which one or more throw-away tips are fixed, wherein a bottom cutting edge formed by the one or more throw-away tips extends along a plane perpendicular to a rotation axis. And at least one of the bottom cutting edges has a length that does not generate an unmachined portion at the center of the counterbore surface of the work material when counterbored without a prepared hole. Away rotary cutting tool. 2. The indexable rotary cutting tool according to claim 1, wherein a bottom cutting edge of the indexable insert extends along a straight line passing through a rotation axis. 3. The throw-away rotary cutting tool according to claim 1, wherein the bottom cutting edge of the throw-away insert is made of an ultra-high pressure sintered body that is a separate material from the tip body. 4. The indexable rotary cutting tool according to claim 3, wherein the ultra-high pressure sintered body is mainly composed of diamond. 5. The indexable rotary cutting tool according to claim 3, wherein the ultra-high pressure sintered body is mainly composed of cubic boron nitride. Indexable rotary cutting tools.