JPH0357382Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a throw-away tip that is particularly suitable for use as a cutting edge in a ball end mill or the like.

[Conventional technology]

In recent years, milling tools for various cutting operations on workpieces have been developed, in which one or more throwaways each having a cutting edge made of cemented carbide or the like formed on the tip of a tool body are removably attached. Throwaway tip type milling tools are becoming more and more popular.

FIGS. 16 and 17 show an example of a throw-away chip installed in a conventional milling tool of this type, which is described in Japanese Patent Application Laid-open No. 181502/1983.

In FIGS. 16 and 17, this throw-away tip 1 has a plate shape with an approximately equilateral triangular outer periphery, and cutting edges 3 each having a convex arc shape of equal length are formed on each side of the upper surface 2. ...is being formed.
The tip 4 and the rear end 5 of the cutting edges 3, 3 adjacent to each other on the outer periphery of the throw-away tip 1 are
A notch 6, which is approximately trapezoidal when viewed from the front as shown in FIG. 17, is formed between each of them. Here, the wall surface 7 located on the tip 4 side of the cutting blade 3 that defines the notch 6 is formed so as to be located on the straight line 8 connecting the tip 4 and the arc center of the cutting blade 3. There is.

Further, the tip portion of the cutting edge 3 that is continuous with the wall surface 7 is formed by a convex curved surface 9, and furthermore, the rake surface 10 along the cutting edge 3 of the upper surface 2 is formed from the tip 4 of the cutting edge 3 to the rear end. 5 and is formed by an inclined surface that is inclined toward the lower surface 11 side thereof. At the rear end 5 of the cutting blade 3, a first
As shown in FIG. 4, there is a straight second cutting edge 12 forming an obtuse angle γ with respect to the tangent at the rear end 5 of the cutting edge 3, and a straight line extending from the second cutting edge 12 to the center side of the throw-away tip 2. A locking wall surface 13 is formed which extends to face the wall surface 7 and defines the cutout portion 6 .

The conventional throw-away tip 1 having the above-mentioned configuration has a tip attached to a tool body (end mill body) 15 which is rotatable around an axis O, as shown by chain lines in FIGS. 16 and 17, respectively. The lower surface 11 of the seat 16 is brought into contact with the tool body 15, and the first cutting edge 3 to be involved in cutting is brought into contact with the tool body 15.
Position the clamp screw 1 from the outer circumference to the tip.
7, it is detachably attached. In this state, the second cutting edge 12 located at the rear end 6 of the cutting edge 3 participates in cutting when the tool body 15 is pulled up relative to the workpiece.

The throw-away tip 1 can be assembled by engaging the locking wall surface 13 of the first notch 6 with the protrusion 18 formed on the tool body 15.
It is mounted so that its rotation is prevented. Further, as shown in FIG. 16, this throw-away tip is attached with a positive axial rake angle.

[Problem that the invention attempts to solve]

However, the conventional throw-away tip 1 mentioned above
Now, a trapezoidal notch 6 is formed on its outer periphery, and a wall surface 7 of this notch 6 that is continuous with the tip 4 of the cutting blade 3 is located on a straight line 8 connecting this tip 4 and the center of the arc of this cutting blade 3. In addition, since the convex curved surface 11 is formed at the tip of the cutting edge 3, the effective length of each cutting edge 3 that participates in cutting ends up becoming shorter, and as a result, the cutting radius becomes shorter. The problem was that it ended up being small.

In addition, as shown in Fig. 11, since the apex angle θ at the tip 4 of the cutting blade 3 is 90°, the strength of the cutting edge in this area is low, and therefore breakage and chipping occur particularly at the tip of the cutting blade 3. The drawback was that it was easy to cut and its cutting performance was poor.

The object of this invention is to provide a throw-away chip that solves the above-mentioned problems of the conventional throw-away chip.

[Means for solving problems]

In order to achieve the above object, this invention has the following configuration. That is, the throw-away tip according to this invention has an outer circumferential shape formed into a substantially equilateral triangular plate shape, and a cutting edge that draws a convex arc on each side of the upper surface, each having a radius larger than the radius of the circumcircle of the equilateral triangle. and a V-shaped notch extending from the top surface to the bottom surface between the tip and rear end of the cutting blades that are adjacent to each other, and a wall surface of each notch portion extending from the tip of the cutting blade to the bottom surface. is formed to be inclined toward the rear end side of the adjacent cutting blade with respect to a straight line connecting the tip of the cutting blade and the center of the circular arc of the cutting blade, and furthermore, the The rake surface along the cutting edge is formed by a plurality of continuous inclined surfaces each inclined at a different angle with respect to the upper surface.

〔Example〕

Hereinafter, one embodiment of the throw-away chip of this invention will be described in detail with reference to FIGS. 1 to 10.

1 to 3, the throw-away tip 21 is plate-shaped with an upper surface 22 and a lower surface 23 parallel to each other, and its outer circumferential shape is approximately an equilateral triangle. Cutting edges 25 are formed on each side of the throw-away tip 21, each consisting of a convex arc of equal length and a radius larger than the radius of the circumscribed circle 24 passing through each vertex of the equilateral triangle. There is. Here, the length of the arc of each of these cutting edges 25 is approximately 1/4 of the total circumference formed by the radius of the arc.

Further, the tip 26 and the rear end 2 of the cutting edges 25, 25 adjacent to each other on the outer periphery of the throw-away tip 21 are
7, V-shaped notches 28 reaching from the upper surface 22 to the lower surface 23 are formed at three equal positions in the circumferential direction. Here, the wall surface 29 extending from the tip 26 of the cutting edge 25 of each of the above-mentioned notches 28 to the lower surface 23 is as follows:
As shown in FIG. 6, the cutting blade 25 is inclined at an angle α toward the rear end 27 side of the adjacent cutting blade 25 with respect to a straight line 30 connecting the tip 26 of the cutting blade 25 and the center of the circular arc of the cutting blade 25. It is formed by Thereby, the tip portion of the cutting edge 25 is formed such that the apex angle θ ₁ at the tip 26 is an obtuse angle.

Then, from the tip 26 of the cutting blade 25 to the upper surface 22
The rake face 31 along the cutting edge 25 is formed by two inclined surfaces 32 and 33 whose inclination angles with respect to the upper surface 22 gradually decrease from the tip 26 toward the upper surface 22. As a result, a rising surface 35 is formed on the side of the rake surface 31 near the tip 26 of the cutting blade 25, which is connected to the other wall surface 34 that defines the notch 28 together with the wall surface 29, and reaches the upper surface 22. has been done.
Further, the boundary between the inclined surfaces 32 and 33 and between the inclined surfaces 32 and 33 and the upper surface 22 or the wall surface 29 is chamfered into a rounded shape.

Further, as shown in FIG. 9, the angle β between the tangent at the rear end 27 of the cutting blade 22 and the rising surface 35 is an obtuse angle, and the side between the rising surface 35 and the upper surface 22 A second cutting edge 38 is formed. This second cutting edge 38 and the cutting edge 25
A nose 36 is formed at the intersection with the rear end 27. Note that the reference numeral 37 in the figure indicates a mounting hole for mounting the throw-away tip 21 on the tool body.

The throw-away tip 21 having the above-mentioned configuration is, as shown in FIGS. 3 to 5,
The lower surface 23 of the tool body (end mill body) 41 held rotatably around the axis O is brought into contact with the tip mounting seat 42 formed at the tip of the tool body 41, and the clamp screw is tightened with a positive axial rake angle. It is detachably attached via 43. Here, the throw-away tip 21 connects the wall surfaces 30 and 34 of one notch 28 to the tool body 41.
By engaging with the convex portion 44 formed at the relevant location, the rotation is prevented.

Moreover, the throwaway tip 21 is the fourth
As shown in the figure, the distance E between the tip 26 of the cutting blade 25 and the axis O is about 0 to 0.3 mm, so that the tip 26 passes very close to the axis O. It is being In this case, as shown in FIG. 3, the throw-away tip 21 is arranged on the tip seat 43 so that the adjacent cutting edge 25, which does not participate in cutting, does not interfere with the workpiece 45. . When the tool body 41 is pulled up in this state, the nose 36 connected to the rear end 27 of the cutting blade 25
The second cutting edge 38 also participates in cutting the workpiece 45.

Next, the functions and effects of the throw-away chip 21 will be explained in detail in comparison with the conventional throw-away chip 2 described above based on FIGS. 6 to 15. Of these figures, FIGS. 6 to 10 each show the throw-away tip 21 of this invention, and FIGS. 11 to 15 show the conventional throw-away chip 21 shown in FIGS. 16 and 17, respectively. This shows Chip 1.

(a) As shown in FIG. 11, in the conventional throw-away chip 1, the wall surface 7 of the notch 6
is formed so as to be located on the straight line 8 connecting the tip 4 of the cutting blade 3 and the center of the circular arc of this cutting blade 3.
The apex angle θ at the tip 4 of is 90°.

On the other hand, in the throw-away tip 21 of the above embodiment, as shown in FIG.
An angle α is made toward the rear end 27 side of the adjacent cutting blade 25 with respect to the straight line 30 connecting the center of the circular arc of No. 5.
Since it is formed to be inclined, the apex angle θ ₁ at the tip 26 of the cutting edge 25 of the throw-away tip 21 can be made obtuse.

Therefore, this throw-away chip 21 is different from the conventional throw-away chip 1 described above.
Compared to the above, it is possible to obtain high cutting edge strength, thereby preventing the occurrence of breakage or chipping at the tip of the cutting edge 25. Further, since the wall surface 29 is formed to be inclined with respect to the straight line 30, the notch portion 28 can be made small, so that the effective length of the cutting blade 25 can be increased. Therefore, the cutting radius of the end mill equipped with this throw-away tip 21 can be made even larger.

(b) As shown in FIG. 12, in the conventional throw-away tip 1, the rake face 10 along the cutting edge 3 is an inclined surface that slopes from the tip 4 of the cutting edge 3 toward the rear 5 toward the lower surface 11 side. Since the tool body is formed with a positive axial rake angle, the cutting edge 3 is
The distance from the axis O of the cutting blade 3 increases from the tip 4 to the rear end 5. Also,
Especially at the rear end 5 of the cutting edge 3, its upper and lower surfaces 2,1
Since the thickness dimension between 1 and 1 becomes smaller, the strength of the cutting edge deteriorates.

On the other hand, in the throw-away tip 21 of the above embodiment, as shown in FIG.
A rake face 31 of the cutting blade 3 is formed so that the portion other than its tip portion is flush with the upper surface 22.

Therefore, with this throw-away tip 21, even when attached to the tool body with a positive axial rake angle, the tip 26 of the cutting edge 25 is larger than that of the conventional throw-away tip 1.
Since the distance of the cutting edge 25 from the axis O toward the rear end 27 is small, the machining error is small, and excellent machining accuracy can be obtained. Furthermore, since the chip thickness is constant from the tip 26 to the rear end 27 of the cutting blade 25, uniform and high cutting blade strength can be obtained along the cutting blade 25.

(c) As shown in FIGS. 13a, b, and c, in the conventional throw-away tip 1, the rake face 1
0 is formed in a cross-sectional shape as shown in FIG. 2B at the center of the cutting blade 3, and as shown in FIG. That is, in the case of this throw-away tip 1, the rake face 1 at the rear end 5 of the cutting edge 3
A rising surface 10a leading to the upper surface 22 is formed on the side of the 0, and this rising surface 10a becomes an obstacle to chip evacuation, resulting in poor chip evacuation performance and also contributing to the occurrence of vibration and chatter. .

On the other hand, in the throw-away tip 21 of the above embodiment, as shown in FIG.
A rake face 31 along the cutting edge 25 is formed flush with the upper surface 22 except for its tip portion.

Therefore, in this throw-away tip 21, there is no obstacle on the rake face 31 that prevents the ejection of chips, and the chips can thus be naturally curled, compared to the conventional throw-away tip 1 described above. This allows for much better chip evacuation.

(d) As shown in FIG. 14, in the conventional throw-away tip 1, a straight second cutting edge is provided at the rear end 5 of the cutting edge 3, forming an obtuse angle γ with respect to a tangent at the rear end 5. 15 is formed. Moreover, as shown in FIG. 16, the cutting edge 3 is formed to be inclined toward the lower surface 11 from the tip 4 toward the rear end 5, so that it can be mounted with a negative axial rake angle, for example. Then, during pull-cutting, the effective relief angle at the second cutting edge 12 becomes insufficient, and so-called second contact occurs, making it impossible to perform cutting.

On the other hand, in the throw-away tip 21 of the above embodiment, as shown in FIG. The angle β between the second cutting edge 38 and the tangent at the rear end 26 of the cutting edge 25 is an obtuse angle. Then, the cutting blade 2
A curved nose 36 is formed at the intersection of the cutting edge 5 and the second cutting edge 38. In addition, the cutting edge 25 is formed along the upper surface 25.

Therefore, even if the throwaway tip 21 is installed with a negative axial rake angle, the effective clearance angle at the second cutting edge 38 will not be insufficient.
Pull cutting can be performed. Moreover,
Since the nose 36 has a curved surface, it is possible to obtain a more excellent chipping prevention effect than the conventional throw-away tip 1.

(E) As shown in FIG. 15, in the conventional throw-away tip 1, a locking wall surface 13 is formed on the rear end 5 side of the cutting blade 3, facing the wall surface 7 and extending toward the center thereof. By engaging this locking wall surface 13 with the protrusion 18 of the tool body 15, rotation thereof is prevented.

On the other hand, in the throw-away tip 21 of the above embodiment, as shown in FIG. Rotation of the main body 41 is prevented by contacting the convex portion 44 of the main body 41.

For this reason, generally, this type of round or nearly round throw-away tip will easily turn clockwise during cross-feed cutting if it is a clockwise rotating tool.
Also, in vertical feed cutting, it is easy to turn counterclockwise, so
This throw-away tip 21 has a superior tip rotation prevention effect compared to the conventional throw-away tip 1.

(f) Also, the throwaway tip 2 of this embodiment
1, the tip of the cutting blade 25 has two inclined surfaces 32,
33, the cutting load gradually increases as cutting progresses, so this cutting edge 2
The cutting load is not applied to the cutting edge 5 all at once, and therefore, the impact force applied to the cutting edge 25 can be significantly alleviated. Furthermore, processing is easier than in the case where the tip portion is formed with a curved surface.

(G) Furthermore, in the throw-away tip 21 of this embodiment, there are
Since the boundary portion between the upper surface 22 or the wall surface 29 is rounded and chamfered, chipping of this portion can be prevented.

In the above embodiment, an example was described in which the throw-away tip 21 was mounted with the tip 26 of the cutting blade 25 positioned near the axis O of the tool body 41, but the present invention is not limited to this. Similar effects can be obtained even when applied to a so-called radius type end mill in which the tip 26 does not pass near the axis O.

Further, in the above embodiment, a so-called positive type throw-away chip 21 was described in which the side surface 38 serving as a relief surface forms an acute angle with the top surface 22, but the present invention is not limited to this. A vertical so-called negative type may also be used.

[Effect of idea]

As explained above, the throwaway chip of this invention has an outer periphery shaped like a substantially equilateral triangular plate, and a convex arc with a radius larger than the radius of the circumcircle of the equilateral triangle is drawn on each side of the upper surface. In addition to forming a cutting edge, a V-shaped notch reaching from the upper surface to the lower surface is formed between the tip and rear end of the cutting edge that are adjacent to each other, and from the tip of the cutting edge of each notch to the lower surface. A wall surface extending from the tip of the cutting blade to the upper surface is formed so as to be inclined toward the rear end of the adjacent cutting blade with respect to a straight line connecting the tip of the cutting blade and the center of the circular arc of the cutting blade. The rake face extending along the cutting edge is formed by a plurality of inclined surfaces each inclined at a different angle with respect to the upper surface.

Therefore, in the case of the throw-away tip of this invention, the above-mentioned notch can be formed into a small size, and as a result, the effective length of the blade can be increased.
Therefore, the cutting radius of the attached tool can be increased.

Furthermore, since the apex angle at the tip of the cutting blade can be made obtuse, the strength of the cutting blade can be increased, and thereby the effect of preventing chipping and chipping of the cutting blade can be improved. Furthermore, since the rake face is formed flush with the upper surface, chip evacuation can be improved, and cutting performance can be greatly improved.

[Brief explanation of drawings]

Figures 1 to 10 show an embodiment of the throw-away tip of this invention. Figure 1 is a front view, Figure 2 is a side view, and Figure 3 shows the rotating throw-away tip and the workpiece. Figure 4 is a front view showing the throw-away tip attached to the end mill body, Figure 5 is a side view of the same, and Figures 6 to 10 are views of the throw-away tip attached to the end mill body. This is to explain the action and effect.
11 to 15 are respectively a front view and FIGS. 11 to 15 are for explaining the function and effect of the conventional throw-away tip, and FIGS. 11 to 13a, 14 and 15 are front views, respectively. Figure 13b is the same as Figure 13a.
Fig. 13c is a sectional view taken along the - line in Fig. 13a.
16 and 17 show a conventional throw-away tip, with FIG. 16 being a side view and FIG. 17 being a front view thereof. 21... Throwaway tip, 22... Top surface, 23... Bottom surface, 24... Circumcircle, 25... Cutting edge, 26... Tip, 27... Rear end, 28... Notch, 31... Rake Surface, 29, 34...Wall surface, 3
2, 33... Inclined surface, 36... Nose, 38...
Second cutting blade, 41...tool body (end mill body),
42...Chip mounting seat, 43...Clamp screw,
O... Axis line.

Claims (1)

[Scope of utility model registration request] The outer periphery is approximately a plate shape of an equilateral triangle, and each side of the upper surface thereof is formed with a cutting edge that draws a convex arc with a radius larger than the radius of the circumscribed circle of the equilateral triangle, and the cutting edges that are adjacent to each other are A V-shaped notch extending from the upper surface to the lower surface is formed between the tip and the rear end, and a wall surface of each notch from the tip of the cutting blade to the lower surface is connected to the tip of the cutting blade. The rake face is formed to be inclined toward the rear end side of the cutting blade adjacent to the straight line connecting the arc center of the cutting blade, and is along the cutting blade from the tip of the cutting blade to the upper surface. A throw-away chip characterized by being formed by a plurality of continuous inclined surfaces each inclined at a different angle with respect to the upper surface.