JPH0871834A - Throw away tip - Google Patents

Abstract

PURPOSE: To increase the cutting edge strength of a tip and prolong the service life. CONSTITUTION: In a throw away tip of almost square plate shape, a main cutting edge 13 and an auxiliary cutting edge 15 inclined at a micro angle to the main cutting edge 13 are provided between two adjacent corner parts of the upper face 12. As the flank relief of the main cutting edge 13, the first flank relief 23 (twisted flank relief) of the main cutting edge 13 is provided in such a state that a clearance angle λ is gradually increased from 0 deg. to the positive clearance angle θ1 of the first flank relief 19 of the auxiliary cutting edge 15 from the tip side toward the rear end side. The cutting face 33 of the main cutting edge 13 corresponding to the flank relief 23 is provided at the down inclined face 28 of the breaker groove of the upper face 12, and the rake angle is gradually decreased from the tip side toward the rear end side according to the increase of the clearance angle of the first flank relief 23 of the main cutting edge 13 so as to set the cutting edge angle μ of the main cutting edge 13 to an angle within a specified range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away tip mounted on a cutting tool such as a face mill and an end mill.

[0002]

2. Description of the Related Art Conventionally, for example, as a throw-away tip of the kind which is mounted on the outer peripheral portion of the tip of a cutting tool and can perform a right-angle cutting (90 degree shoulder wall cutting) of a work material, for example, FIG.
As shown in FIGS. 0 and 11, there is a rectangular plate-shaped tip 2 attached to the outer peripheral side of the tip of the front milling cutter 1. As shown in FIG. 10, the throw-away tip 2 has an upper surface 4 that faces a lower surface 3 that forms a seating surface, and its four circumferential side surfaces 5 are flat surfaces that incline outward from the lower surface 3 toward the upper surface 4. I am doing it. The ridge line where each side surface 5 and the upper surface 4 intersect forms a main cutting edge 6, and a sub cutting edge 7 is formed in the vicinity of a corner portion 4a on the same ridge line of each main cutting edge 6. Then, the upper surface 4 forms a rake surface, and the side surface 5 forms a flank of the main cutting edge 6 and the sub cutting edge 7, and the main cutting edge flank and the sub cutting edge flank are on the same surface (side surface 5). Is formed in. A screw hole 8 is formed in the center of the upper surface 4 so as to penetrate the upper and lower surfaces and mount and fix the chip 2 on the face mill 1.

When attaching such a throw-away tip 2 to the seat portion at the outer peripheral side tip of the front milling cutter 1,
The cutter body is positioned with a positive axial rake angle so as to form a positive angle α with respect to the rotation axis L of the cutter body. Moreover, the cutter body is positioned with a negative radial rake angle so as to form a negative angle β with respect to the radial axis M of the cutter body. When attempting to cut the work W with such a cutter 1 at a right angle (90 degree shoulder wall cutting), as shown in FIG. 11, with the main cutting edge 6 located on the cutter outer peripheral side of the throw-away tip 2, The work piece W is cut so as to form a right-angled wall surface, and the auxiliary cutting edge 7 on the outer side of the ridge line located on the tip side is formed into a square plate shape because the cutting angle is formed by the positive axial rake angle and the negative radial rake angle. Right angle shaving can be performed with the tip 2.

[0004]

However, the throw-away tip 2 as described above is mounted on the cutter so that the axial rake angle is positive and the radial rake angle is negative, and moreover, the main cutting edge 6 and the sub cutting edge are provided. Since the clearance angle of the blade 7 is on the same plane (side surface 5), the clearance angle of the main cutting edge 6 is excessively positive. As a result, the cutting edge angle is small, the cutting edge strength is small, and chipping is likely to occur, resulting in a short life of the chip.

In view of such circumstances, an object of the present invention is to provide a throw-away tip which has high cutting performance, can increase the cutting edge strength, and can greatly improve the life thereof. To do. Another object of the present invention is to provide a throw-away tip that can be cut at right angles, has high cutting performance, can increase the cutting edge strength, and can significantly improve its life. .

[0006]

A throwaway tip according to the present invention has a ridge line portion where a first surface and a second surface intersect with each other, and the first surface is a rake surface,
In the throw-away tip where the second surface is the flank, as the clearance angle of the flank increases along the cutting edge, the rake angle of the rake face corresponding to this flank across the cutting edge becomes smaller. It is characterized by being formed into.

In the throw-away tip according to the present invention, the ridge line portion of the upper surface facing the seating surface forms a cutting edge, the upper surface is a rake surface, and the side surface between the seating surface and the upper surface is a flank surface. In the throw-away tip, a sub cutting edge is provided near one corner of the ridge between two adjacent corners on the upper surface, and a main cutting edge is provided toward the other corner. As a flank of the blade, there is a twist flank formed by changing the flank angle so that it gradually increases along the main cutting edge, and a rake that corresponds to the flank with the main cutting edge sandwiched. The surface is characterized by being formed so that the rake angle becomes gradually smaller as the clearance angle of the twist flank surface increases. Further, the clearance angle of the twist flank is a negative surface of 0 degree in the boundary area with the other corner portion, and is gradually increased in the positive direction along the main cutting edge in the direction away from the other corner portion. May be.

The rake face is formed as a descending inclined surface from the main cutting edge side of the breaker groove formed on the upper surface along the main cutting edge toward the center of the upper surface. A small flat land is formed on the ridge portion of the upper surface, and the flat land is formed wide from the auxiliary cutting edge to the corner portion. On the downward sloping surface that forms the rake surface, a convex portion that rises from the wide flat land into the breaker groove is formed. The twist flank is set with a predetermined width in the thickness direction of the tip from the main cutting edge,
Second main cutting edge formed between the twist flank and the seating surface
The flank may be formed in a plane shape with a clearance angle larger than the clearance angle of the twist flank.

The throw-away tip has a substantially square plate shape in a plan view, a main cutting edge and a sub-cutting edge are formed on the ridges of the four edges of the upper surface, and a corner edge is formed on each corner, and they are adjacent to each other. The two main cutting edges are orthogonal to each other, and between two adjacent corner blades, the sub cutting edge is formed so as to be inclined to the inside of the chip by a small angle with respect to the main cutting edge. In a cutting tool in which one or more indexable inserts are mounted on the outer peripheral side of the tip of the tool body so that the radial rake angle is negative and the axial rake angle is positive, the indexable insert is one of the above. The throw-away tip described in.

[0010]

[Function] Since the cutting edge angle is set to a predetermined size over the entire length of the cutting edge, when the cutting edge is attached to the cutting tool and cut, regardless of the leading end side portion or the trailing end side portion of the cutting edge. Alternatively, the strength of the cutting edge is high regardless of the clearance angle of the cutting edge depending on the attitude of the tip. When the throw-away tip is mounted on the cutting tool so that the radial rake angle becomes negative and the axial rake angle becomes positive, the main cutting edge that forms the outer peripheral edge cuts from the tip side to the base side. It is inclined in a direction closer to the rotation axis of the tool, and accordingly, the twist flank of the main cutting edge changes so that the clearance angle gradually increases as it goes from the tip toward the base along the main cutting edge. By doing so, it is possible to avoid this flank contacting the machined wall surface of the work material, and since the rake angle of the rake face of the main cutting edge is gradually reduced accordingly, the cutting edge angle is increased and The fluctuation of the size can be set small, and the cutting edge strength of the main cutting edge is high.

Further, by minimizing the clearance angle of the twist flank face, the cutting edge angle of the main cutting edge can be set larger, the cutting edge strength is high, and the cutting performance is improved. The flat land can increase the strength of the cutting edge, and by forming the auxiliary cutting edge wide from the corner portion, it is possible to strengthen the auxiliary cutting edge that is easily damaged during cutting. Since the convex portion is formed on the descending inclined surface of the wide portion, the chips generated at the time of low cutting can be easily curled. By limiting the twist flank to a predetermined width, the second main flank of the main cutting edge can be made large, and if this is used as the side surface receiving portion of the seat portion when the chip is mounted, it will contact at a position closer to the rake face. Therefore, the seating stability is good. When this throw-away tip is attached to the outer peripheral tip side of the cutting tool and used for cutting, the main cutting edge on the outer peripheral side performs right-angle wall surface cutting, and the sub cutting edge on the tip side performs incision cutting. Therefore, it is possible to perform right-angle cutting of the work material while maintaining high cutting edge strength.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 9. However, the same parts as those of the above-mentioned prior art are designated by the same reference numerals and the description thereof will be omitted. 1A and 1B show a throw-away tip according to this embodiment, wherein FIG. 1A is a plan view thereof, FIGS. 1B and 1C are side views corresponding to this plan view, and FIG. ) Line A-A sectional view, FIG. 3 is a partial cross-sectional view taken along the line BB of FIG. 1A, and FIG.
-C line partial sectional view, FIG. 5 is a DD line partial sectional view of FIG. 1A, FIG. 6 is an enlarged view of a corner portion of the throw-away tip plane, and FIG. 7 is attached with the throw-away tip according to the embodiment. 8 is a partially cutaway side view of the front milling cutter, FIG. 8 is another side view of the front milling cutter of FIG. 7, and FIG. 9 is a front view of the front milling cutter of FIG. 7. In FIG. 1, a throw-away tip 10 according to this embodiment has a substantially rectangular (substantially square in the figure) plate shape, and an upper surface 1 facing a lower surface 11 forming a seating surface.
2 and. A main cutting edge 13 is formed on each of the ridges forming the four sides of the upper surface 12, and an arcuate corner blade 14 is provided on each corner. The main cutting edges 13 of two adjacent ridges are orthogonal to each other (see FIG. 6).

Then, between the main cutting edge 13 and the one corner edge 14 at each ridge portion, an inwardly small angle γ (for example, 1 to 5 degrees) with respect to the main cutting edge 13 is provided on the upper surface 12. An inclined auxiliary cutting edge (cleaning blade) 15 is formed, and the auxiliary cutting edge 15 is smoothly connected to the corner blade 14. In addition, as shown in FIGS. 1 (b) and 1 (c), the four circumferential side surfaces 18 between the lower surface 11 and the upper surface 12 have a clearance angle sequentially from the upper surface 12 to the lower surface 11 for each cutting edge region. Two large flanks are formed.

That is, on the side surface 18 in the region of each sub-cutting edge 15, a constant width t (for example, about 0.5 to 1.5 mm) that intersects the sub-cutting edge 15 and extends along each sub-cutting edge 15. ) Is a flat sub-cutting blade first flank 19 having a constant clearance angle θ1 (for example, 15 degrees), and the lower region thereof has a larger clearance angle θ2 than the first flank surface 19 (for example, ,
20 degrees) is set as the secondary cutting edge second flank 20. Then, on the side surface 18 in the area of each corner blade 14,
A portion of the constant width t that intersects the corner blade 14 and extends along the corner blade 14 has a clearance angle of θ1 (positive position) from the adjacent sub cutting edge 15 side toward the adjacent main cutting edge 13 side. It is the first flank 21 of the corner blade that can be gradually changed from the surface) to 0 degree (negative surface). In addition, the lower area is
It is a corner blade second flank 22 in which the same clearance angle θ2 as the auxiliary cutting edge first flank 20 is set. The corner blade first and second flanks 21 and 22 are each formed in the shape of a cylindrical side surface that is inclined outward.

On the side surface 18 in the area of the main cutting edge 13, a portion having a constant width t that intersects the main cutting edge 13 and extends along the main cutting edge 13 is the main cutting edge 13 and the corner edge 14. The clearance angle θ3 is set to 0 degree (negative surface) in the boundary area, and the clearance angle θ3 is the clearance angle θ1 (positive surface) of the secondary cutting edge first flank 19 in the boundary area with the auxiliary cutting edge 15. The main cutting edge first flank 23 is gradually changed so as to coincide with.
That is, the main cutting edge first flank 23 has a clearance angle along the main cutting edge 13 from the boundary area with the corner blade first flank 21 to the boundary area with the sub cutting edge first flank 19. Is formed so as to smoothly change from 0 degree to θ1 to form a twist flank. Further, the lower region of the main cutting edge first flank 23 is larger than the clearance angle θ3 of the main cutting edge first flank 23,
It is a flat main cutting edge second flank 24 which is set to the same clearance angle θ 2 as the auxiliary cutting edge first flank 20.

Further, on the upper surface 12, a flat land (rake surface land) 26 having a small width and parallel to the lower surface 11 is formed over the entire circumference from the ridge line portion of the entire circumference forming each cutting edge toward the center side. Moreover, the land 26 has a substantially arc-shaped wide land portion 2 extending from the area of each sub-cutting edge 15 to the corner edge 14.
6a is formed. As shown in FIG. 2 as a sectional view taken along line AA of FIG. 1A, a recess 27 is formed in the inner region of the flat land 26 on the upper surface 12. The downward slope 28 having a downward slope, the upward slope 29 having a short height formed over the entire circumference from the lowermost part of the slope 28, and the plan view following the upward slope 29. It is formed in a substantially square shape and has a central bottom surface 30 parallel to the lower surface 11. This center bottom 30
Has a smaller distance from the lower surface 11 than the ridges of the main cutting edge 13 and the like, and has a screw hole 16 for fixing a chip screw in the center thereof (a clamping surface or the like may be used). Also, the center bottom surface 30
1 is a plan view shown in FIG. 1 (a), it is located at a slight angle with respect to the upper surface 12. Therefore, the breaker groove 31 constituted by the descending inclined surface 28 and the ascending inclined surface 29 has a main cut. Blade 1
On the other hand, the width is gradually changed so that the width becomes maximum near the boundary with the corner blade 14 and becomes minimum near the boundary with the auxiliary cutting edge 15.

Further, each sub-cutting edge 15 is formed on the descending inclined surface 28.
A convex portion 32 having a curved surface of a substantially inverted conical surface is provided so as to project from the wide land portion 26a toward the lowermost portion thereof. As shown in the cross-sectional view of FIG. 3, the convex portion 32 has a concave curved surface with a radius R1 at the connecting portion with the downward slope 28, and the convex portion 32 has a convex curved surface with a radius R2. 15
When the low cutting depth is cut by the main cutting edge 13 which is connected via the corner blade 14, the breaker is configured to curl the chips.

Further, the descending inclined surface 2 corresponding to each main cutting edge 13
When the area 8 is the main cutting edge rake face 33, the main cutting edge rake surface 33 has a clearance angle λ of the corresponding main cutting edge first flank (twist flank) 23 with the main cutting edge 13 interposed therebetween. Since the rake angle δ changes in accordance with the change, the change in the cutting edge angle μ is suppressed to be small over the entire length. That is, in the boundary area between the corner blade 14 and the main cutting edge 13, the clearance angle λ of the main cutting edge flank 23 is set to the minimum 0 degree (negative surface), and the main cutting edge rake face corresponding to this is set. The rake angle δ of 33 is the maximum δ1 (see FIG. 3).
In the region slightly separated from the corner blade 14, as shown in FIG. 4, the clearance angle λ of the first cutting edge first flank 23 is a minute angle λ1 (≧ 0), and the rake angle of the main cutting edge rake face 33 is small. δ is set to δ2 (<δ1). Then, in the cross section near the center of the main cutting edge 13 (see FIG. 2), the clearance angle λ of the first cutting edge first flank 23 is λ2 (> λ1), and the rake angle δ of the main cutting edge rake face 33 is δ3 (<δ2). Further, in the boundary area with the sub cutting edge 15, as shown in FIG. 5, the cutting edge first flank 2
The clearance angle λ of 3 is λ3 (= 15 degrees> λ2), and the rake angle δ is δ4 (<δ3).

Therefore, as the main cutting edge 13 moves from the boundary with the corner blade 14 toward the boundary with the sub cutting edge 15, the clearance angle λ of the primary cutting edge first flank 23 is 0 ≦ λ1 <λ2 <λ3 ( =
15) and accordingly, the rake angle δ of the main cutting edge rake face 33 decreases as δ1>δ2>δ3> δ4. Therefore, the cutting edge angle μ of the main cutting edge 13 is the main cutting edge first flank 23 and the main cutting edge rake surface 33 over the entire length thereof.
Can be set to a certain size (larger than that of the prior art) whose fluctuation is suppressed within a predetermined range (may be set to the same cutting edge angle over the entire length). The edge strength can be enhanced.

A state in which such a throw-away tip 10 is mounted on the front milling cutter 1 is shown in FIGS. 7 to 9. In the mounted state of this tip 10, as shown in FIG. 7, the auxiliary cutting edge 15 is located outside the tip surface as a front cutting edge, and the main cutting edge 13 of the adjacent ridge line portion on the outer peripheral tip side rotates the cutter body. The outer peripheral blade is located parallel to the axis L (in the figure). Further, the positioning is performed such that the positive axial rake angle α is as shown in FIG. 8 and the negative radial rake angle β is as shown in FIG. In particular, FIG.
In the chip 10 having the axial rake angle α shown in, with respect to the side surface 18 located on the outer peripheral surface side of the cutter 1,
The main cutting edge 13 forming the outer peripheral edge is located on the tip end side in the axial direction so as to form a right-angled wall surface of the work material W, and the sub cutting edge 15 not involved in cutting is located on the base end side (rear end side). become. Moreover, since the sub cutting edge first flank 19 which is the flank on the proximal end side is closer to the axis L than the main cutting edge first flank 23, the sub cutting edge first flank 19 has a main cutting edge. By providing a positive clearance angle θ1 larger than that of the first flank 23 of the blade, it is possible to prevent the clearance surface 19 from coming into contact with the machining wall surface of the workpiece W during cutting.

In the area of the main cutting edge 13, the clearance angle λ of the primary cutting edge first flank 23 is set to the primary cutting edge first flank 23 because it gradually moves away from the axis L from the proximal end side toward the distal end direction. The clearance angle θ1 of the clearance surface 19 may be gradually decreased. For this reason, in the present embodiment, the main cutting edge first flank 23 is provided with a clearance angle λ.
Is a twist flank that gradually changes from the positive angle θ1 to 0 degrees in the distal direction from the base end side (the side of the secondary cutting edge first flank 19) to set the minimum necessary clearance angle λ. Moreover,
The main cutting edge rake face 33 corresponding to the main cutting edge first flank 23 with the main cutting edge 13 sandwiched is provided with the rake angle δ from the base end side toward the tip direction of the main cutting edge first flank 23. Since the clearance angle λ is gradually increased (δ4 to δ1 degree) as the clearance angle λ is decreased (λ3 to 0 degree), the cutting edge angle of the main cutting edge 13 is set to a large angle within a predetermined range regardless of the change of the clearance angle λ. Can be set to enhance the strength of the cutting edge. In this way, the cutting edge angle of the main cutting edge 13 can be set large over the whole.
In particular, the main cutting edge 13 has a larger length than the sub cutting edge 15 and has a large contact area with the work material W in order to form a right-angled wall surface by cutting. The life of the chip 10 can be significantly improved.

Further, the second flank 24 of the main cutting edge is fixed at a constant angle θ2.
The cutter body 1a shown in FIG.
Two adjacent side surface receivers 35a, 35 of the seat portion 35 of
In b, when supporting each side surface 18 of the throw-away tip 10, it is possible to secure the stability of seating while forming a necessary minimum twist escape surface.

As described above, according to this embodiment, due to the mounting posture of the throw-away tip 10 on the cutting tool, the main cutting edge first flank 2 of the main cutting edge 13 (which forms the outer peripheral edge).
Even if the clearance angle λ of 3 is gradually increased from the front end side to the rear end side, the main cutting edge rake face 33 is correspondingly increased.
Since the rake angle δ has been gradually reduced, the main cutting edge 1
It is possible to maintain the blade edge angle of 3 at a predetermined size over the whole, to increase the blade edge strength, and to greatly improve the life of the tip. In particular, since the rake angle δ of the main cutting edge rake face 33 on the tip side is the largest, the cutting performance at low cutting depth is good, and the clearance angle of the main cutting edge first flank 23 in this region is almost 0 (negative). Since it is close to the surface), the strength of the cutting edge can be kept relatively high. Further, by forming the wide land portion 26a in the area of the sub cutting edge 15 of the flat land 26, it is possible to strengthen the cutting edge strength from the sub cutting edge 15 which is likely to be damaged during cutting to the corner blade 14 of the nose portion. . Moreover, by providing the convex portion 32 from the wide land portion 26a to the descending inclined surface 28, it is possible to curl the chip as a breaker at the time of the low cutting by the main cutting edge 13 and improve the chip discharging property. . Further, since the convex portion 32 is formed in the shape of an inverted conical surface even when making a deep cut, it is possible to curl the chips and guide them toward the base end side, resulting in good chip discharge.

Further, in each of the above-mentioned embodiments, the corner blade 14 is formed in an arc shape in a plan view, but it may be formed in a chamfer. In the embodiment, the main cutting edge 13
Although the flanks of the secondary cutting edge 15 and the corner blade 14 are also two-staged, the primary cutting edge first
One-step configuration in which the flank 23 extends to the lower surface 11 (or 3
It is also possible to have a configuration of more than one step). Further, in the above-described embodiment, the main cutting edge first flank 23 of the throw-away tip 10 has a gradual increase in clearance angle from the front end side toward the rear end side, and the main cutting edge rake face 33 accordingly. Although the number is reduced, the invention is not limited to this configuration, and the flank 23 and the rake face 33 are not limited thereto.
The respective increasing / decreasing directions may be opposite to those in the embodiment. In short, the throw-away tip of the present invention may be configured so that the clearance angle and the rake angle of the cutting edge increase or decrease with each other so as to suppress the variation in the size of the cutting edge angle.

[0025]

As described above, in the throw-away tip according to the present invention, as the clearance angle of the flank increases along the cutting edge, the rake angle of the rake face corresponding to the flank across the cutting edge becomes larger. Since it is formed to be small, as the clearance angle or rake angle increases or decreases, the corresponding rake angle or clearance angle decreases or increases,
The cutting edge angle can be formed large regardless of the cutting edge portion, and the cutting edge strength and the chip life can be improved. Further, the throw-away tip according to the present invention is provided with a sub-cutting edge near one corner between two adjacent corners on the upper surface, and a main cutting edge is provided toward the other corner. As the flank of the main cutting edge, a twist flank with a gradually increasing clearance angle is provided along the main cutting edge, and the rake face corresponding to the twist flank with the main cutting edge is the flank. Since the rake angle of the main cutting edge gradually decreases as the clearance angle of the main cutting edge increases, even if the relief angle of the main cutting edge twist flank or the rake angle of the main cutting edge rake surface changes, The angle of the cutting edge can be maintained at a predetermined size over the entire cutting edge, the strength of the cutting edge can be increased over the entire cutting edge, and the life of the tip can be greatly improved.

Further, since the clearance angle of the twist flank surface gradually increases from the negative surface of 0 degree toward the direction away from the other corner along the main cutting edge, in particular, the main cutting edge on the tip side. The rake angle of the rake face is the largest, the cutting performance is good at low depth of cut, and the clearance angle of the twist flank face in this region is negative, so the edge strength can be kept high.
In addition, a small flat land is formed on the ridge line on the upper surface, and this flat land is formed wide from the sub cutting edge to the corner, so that the cutting edge is easily broken from the sub cutting edge to the corner. Strength can be enhanced. In addition, on the downward sloping surface that forms the rake face, since a convex portion that rises from the wide flat land into the breaker groove is formed, it is possible to curl chips as a breaker at the time of low cutting by the main cutting edge. Good chip discharge performance. In addition, even when making a deep cut, the chips can be curled by the convex portion and guided to the base end side, and the chip discharge performance is good.

[Brief description of drawings]

FIG. 1 shows a throw-away tip according to an embodiment of the present invention, in which (a) is a plan view, (b), (c).
[Fig. 3] is a side view corresponding to a plan view.

FIG. 2 is a cross-sectional view taken along line AA of the throw-away tip plan view shown in FIG.

FIG. 3 is a partial sectional view taken along the line BB of the throw-away tip plan view shown in FIG.

FIG. 4 is a partial cross-sectional view taken along line CC of the throw-away tip plan view shown in FIG.

FIG. 5 is a partial cross-sectional view taken along line DD of the throw-away tip plan view shown in FIG.

FIG. 6 is an enlarged view of a corner portion of the throw-away tip plan view shown in FIG.

FIG. 7 is a partially cutaway side view showing a state in which the throw-away tip according to the embodiment is mounted on the front milling cutter.

FIG. 8 is a side view showing a state where the throw-away tip is mounted on the front milling cutter as seen from the outer peripheral side.

9 is a front view of the front milling cutter shown in FIG. 7. FIG.

FIG. 10 is a perspective view of a conventional throw-away tip.

FIG. 11 is a partial cross-sectional view showing a state in which a conventional milling cutter is mounted on a front milling cutter at a right angle.

[Explanation of symbols]

1 ... Face mill, 10 ... Throwaway tip, 11
... Lower surface, 12 ... Upper surface, 13 ... Main cutting edge, 14 ... Corner blade, 15 ... Sub cutting edge, 18 ... Side surface, 19 ... Sub cutting edge first flank, 23 ... Main cutting edge first flank, 24 ... Main cutting edge second flank surface, 28 ... Downward sloping surface, 26 ... Flat land, 26a ... Wide land portion, 32 ... Convex portion, 33 ... Main cutting edge rake surface.

Claims (9)

[Claims] 1. A ridge line portion where a first surface and a second surface intersect forms a cutting edge, and the first surface is a rake surface,
In the throw-away tip in which the second surface is a flank, as the clearance angle of the flank increases along the cutting edge, the rake angle of the rake face corresponding to this flank across the cutting edge is A throw-away tip characterized by being formed to be small. 2. A throw-away tip in which a ridge line portion of an upper surface facing a seating surface forms a cutting edge, the upper surface is a rake surface, and a side surface between the seating surface and the upper surface is a flank surface, A sub-cutting edge is provided near one corner of the ridge between two adjacent corners of the upper surface, and a main cutting edge is provided toward the other corner, which serves as a flank of this main cutting edge. , Formed along with the main cutting edge so that the clearance angle is gradually increased, with a twist flank, the rake face corresponding to the twist flank across the main cutting edge, A throw-away tip formed by changing the rake angle such that the rake angle gradually decreases as the clearance angle of the twist flank increases. 3. The clearance angle of the twist flank is a negative surface of 0 degree in the boundary region with the other corner portion, and the positive angle is gradually increased in the direction away from the other corner portion along the main cutting edge. The throw-away tip according to claim 2, wherein the throw-away tip increases. 4. The rake face is formed as a descending inclined surface from the main cutting edge side of a breaker groove formed on the upper surface along the main cutting edge toward the center of the upper surface. Alternatively, the throw-away tip described in 3. 5. The throw according to claim 2, wherein a flat land having a small width is formed on the ridge portion of the upper surface, and the flat land is formed wide from the sub cutting edge to the corner portion. Away tip. 6. The throw-away tip according to claim 5, wherein a convex portion protruding from the wide flat land into the breaker groove is formed on the descending inclined surface forming the rake surface. 7. The twist flank is set with a predetermined width in the thickness direction of the tip from the main cutting edge, and the second flank of the main cutting edge formed between the twist flank and the seating surface is twisted. The throw-away tip according to any one of claims 2 to 6, wherein the throw-away tip is formed in a plane shape with a clearance angle larger than the clearance angle of the clearance surface. 8. The throw-away tip has a substantially square plate shape in a plan view, wherein the main cutting edge and the sub cutting edge are formed on the ridges of the four edges of the upper surface, and the corner edges are formed on the respective corners. The two adjacent main cutting edges are orthogonal to each other, and between the two adjacent corner edges, the auxiliary cutting edge is formed to be inclined to the inside of the chip by a small angle with respect to the main cutting edge. The throw-away tip according to any one of claims 2 to 7. 9. One or more throw-away tips,
In a cutting tool which is mounted on the outer peripheral side of the tip of the tool body such that the radial rake angle becomes negative and the axial rake angle becomes positive, the throw-away tip is the throw according to any one of claims 2 to 8. A cutting tool that is an away tip.