JP3366751B2 - Indexable tip - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive type throw-away tip mounted on a turning tool, and is particularly excellent in chip control.

[0002]

2. Description of the Related Art Positive type throw-away tips are
Not only external turning but also internal turning. And especially in this internal turning, the chip disposal problem is
It is an important factor for judging the quality of the cutting performance of the tool. Therefore, in the inner diameter turning, a throw-away tip provided with a breaker groove is usually used.

Conventionally, the breaker groove has been formed by grinding on the rake face of the throw-away tip. Forming by grinding yielded only a simple groove shape, and could not sufficiently cope with a wide range of cutting conditions. However, recently, with the improvement of the pressing technique for the powder compact, it has become possible to mold a positive type complex shape by embossing.

Looking at the corner portion of the conventional embossed molded article, in particular, there is a bar-shaped projection extending from the boss surface of the throw-away tip closer to the apex of the corner, or a small projection protruding on the rake surface. There is.

[0005]

However, according to the research conducted by the present inventors, even with the conventional embossed molded product, in the cutting in which thin chips are ejected due to low feed, the chips pass over the projections and are divided. If the cutting is not performed, or if cutting is performed at a high depth of feed with deep cutting, chip clogging may occur, which is not sufficiently satisfactory. The present invention aims to improve the chip disposal performance, and also to prevent the chipping of the cutting edge due to the biting of the discharged chips, which is particularly problematic in the internal turning, and the sharpness that affects the machined surface properties and chattering. It is a thing.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a polygonal flat plate shape, and its cutting edge is a main cutting edge composed of an outer side and an arc shape formed at a corner. In the case of a positive throwaway tip with a relief on the outer circumference, a breaker groove with a land is provided outside the boss surface on the top surface, and the cutting edge is lower than the boss surface. Is formed as in.

The breaker groove is composed of an inclined surface serving as a positive rake surface and an inclined surface rising from the groove bottom to the boss surface.
Further, the breaker groove extends radially from the boss face toward each corner in the corner portion, and the height gradually decreases at the tip, and at least 1 part of which is provided in the middle of the projection and protrudes from both sides. It is formed by a combination with one or more spherical protrusions.

The inclination angle θ ₂ of the inclined surface at the corner is
It is formed so as to be smaller than the inclination angle θ ₁ of the inclined surface in the main cutting edge portion. In addition, even if the land provided in the breaker groove is provided only in the main cutting edge portion, it is not provided in the corner blade. It is characterized by good things.

[0009]

In the present invention, the boss surface is located higher than the cutting edge so that the discharged chips are prevented from directly contacting the parts for mounting the throw-away tip on the tool body. is there.

The inclined surface of the breaker groove serving as a positive rake surface is for ensuring sharpness in the main cutting edge portion. The land of the main cutting edge portion provided for preventing chipping of the cutting edge due to chip biting or the like is preferably a positive land for the same reason as described above.

Since the present invention relates to a throw-away insert that is often used for internal turning, even if it can be applied to a wide range, the cutting edges used are limited to the corner edge and its vicinity. Therefore, the shape of the breaker groove in the vicinity of the corner becomes important. The projection that simply extends from the boss surface to the corner tip as in the past has good chip control in a certain cutting range, but the feed is
When the size is very small, the chips become thin, and the chips get over the projection and are not divided. The spherical projections provided in combination relatively near the corner tip have the action of forcibly separating the chips in the above case, and improve the chip disposal performance.

Further, in cutting with increased depth of cut, particularly with high feed rate, only the protrusion extending from the boss surface to the corner tip is close to the cutting edge at the corner tip and too far from the cutting edge behind the corner, so that the breaker groove is formed. The balance may be poor and chip clogging may occur. By combining this with the spherical projection of the present invention, a breaker wall close to the main cutting edge is provided, and the breaker groove serves as a breaker groove.

The inclination angle of the inclined surface which serves as the positive rake surface of the breaker groove is set to be small at the corner portion to prevent the strength of the structurally weak corner portion from decreasing. When the quality of the machined surface as the inner diameter turning is emphasized, the corner blade is a cutting edge having no land to enhance the sharpness.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings.

1 and 2 are front views of the throw-away tip 1 of the present invention, showing the upper surface which is the rake face of the diamond-shaped tip. The outer edge is a cutting edge, and the cutting edge is formed by a main cutting edge 2 having four sides and an arc-shaped corner edge 3 formed at a corner. And, it is a positive type throw-away tip in which relief is provided on the outer peripheral surface of the cutting edge.

A countersink 4 is formed in the center of the upper surface so as to penetrate from the upper surface to the lower surface. There is a boss surface 5 around the countersink 4, and a breaker groove 6 is formed between the boss surface 5 and the cutting edge. The breaker 6 groove has a shape as shown in FIGS. 3 to 6 in each sectional view in FIG. That is,
In the cross-sectional shape along the line 3A-A in FIG.
It is composed of a land 7 including the main cutting edge 2, an inclined surface 8 which is connected to the land 7 to form a positive rake surface having an inclination angle θ ₁ , and an inclined surface 9 which rises from the groove bottom to the boss surface 5.

The throw-away tip 1 is mounted on the tool body by screwing it with a countersunk screw through the countersink 4, but it is ejected because the boss surface 5 is higher than the main cutting edge 2. This avoids the risk of scrap metal scraping the head of the flat head screw and damaging it. Further, since the positive inclined surface 8 has an effect of improving sharpness and reducing cutting resistance, it is effective in improving the roughness of the machined surface and suppressing chatter which is a problem particularly in the internal turning. For the same reason as above, the land 7 provided for the purpose of preventing damage to the cutting edge due to biting of chips accumulated in the machining hole in the inner diameter turning
It is preferably positive.

In the case of the throw-away tip 1 without the countersink 4, most of them are attached to the tool main body by the presser foot, but the effect that the boss surface 5 is at the high position has the same effect, and the chips are The chance of scraping the presser foot is reduced.

The breaker groove 6 at the corner is shown in FIG.
It is formed by a combination of sectional shapes shown in FIG. Figure 4B
The cross-sectional shape along the line -B is the inclined surface 8 forming a positive rake surface having an inclination angle θ ₂ from the corner blade 3, and the boss surface 5.
It is composed of a protrusion 10 extending toward the tip of the corner more gradually from the boss surface 5 with the height gradually reduced. The cross-sectional shape along the lines 5C-C and 6D-D is composed of a spherical protrusion 11 and a protrusion 12 which are in the middle of the protrusion 10 and partially protruded on both sides, and the protrusion 11 close to the corner tip. Has a smaller spherical diameter than the protrusion 12. Although the number of the spherical projections is two in this embodiment, it may be appropriately changed according to the corresponding cutting conditions and the shape of the tip. In this embodiment as well, the number of adjacent corner portions with obtuse vertical angles is one.

The protrusion 10 has a corner edge 3 at the corner tip.
However, it is disposed apart from the main cutting edge 2 on the boss surface 5 side. Therefore, it shows good chip controllability for cutting with a very shallow depth of cut. But protrusion 1
With only 0, the depth of cut becomes somewhat deeper, and especially when the feed is small, thin and elastic chips pass over the protrusion 10 and become continuous chips without being divided. The spherical protrusion 11 has an action of forcibly separating such chips and curling them.

When the depth of cut is further increased, especially when the feed is large, the protrusion 10 alone forms a breaker groove that is narrow at the tip and too wide on the boss surface 5 side, so the balance as a breaker is poor and chips are self-blocking. The spherical protrusion 12 narrows the breaker groove on the boss surface 5 side so that the breaker groove effectively acts as a breaker. As a result,
Overall balance is improved and chip clogging is eliminated.

In this embodiment, the corner blade 3 does not have the land 7. This is because the emphasis was placed on improving the surface properties and suppressing chattering. However, since the corner with an acute vertical angle is structurally disadvantageous in terms of fracture resistance, the inclination angle θ ₂ of the corner is smaller than the inclination angle θ ₁ of the main cutting edge, and the strength is increased. It prevents the decline.

7 and 8 show another embodiment of the present invention, in which the same parts are designated by the same reference numerals. Figure 7
This is an example in which the number of the spherical projections 11 is one in each corner according to the cutting conditions to be applied. In addition, since the cutting edge reinforcement is prioritized over the sharpness, the corner blade 3 also has a land 7
Is equipped with. FIG. 8 shows the throw-away tip 1 in the shape of a triangular flat plate without a countersink. In this example, the number of spherical protrusions is one, and the corner blade 3 is not provided with the land 7.

[0024]

As described above, according to the present invention, in the positive type throw-away insert, it is possible to realize the chip control capable of dealing with a wide range of cutting conditions used for normal internal turning. The corner edge is strengthened by changing the inclination angle of the breaker groove, but if priority is given to fracture resistance, the corner edge should be provided with a land, and the improvement of machined surface properties and suppression of chatter are prioritized. If you want to make it, you can select the one without land.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

3 is a sectional view taken along the line AA of FIG.

4 is a cross-sectional view taken along the line BB of FIG.

5 is a cross-sectional view taken along the line CC of FIG.

6 is a cross-sectional view taken along the line DD of FIG.

FIG. 7 is a front view showing another embodiment of the present invention.

FIG. 8 is a front view showing another embodiment of the present invention.

[Explanation of symbols]

1 Throw-away tip 2 Main cutting edge 3 corner blades 5 Boss surface 6 breaker grooves 7 land 10, 11, 12 protrusions

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Claims (2)

(57) [Claims] 1. A polygonal flat plate, the cutting edge of which is composed of a main cutting edge 2 having an outer edge and an arcuate corner edge 3 formed at a corner, and a relief is provided on the outer circumference. In the positive type throw-away tip 1, a boss surface 5 is provided on the upper surface, a breaker groove 6 provided with a land 7 is arranged on the outer side thereof, and a cutting edge is formed so as to be lower than the boss surface 5. The breaker groove 6 has an inclined surface 8 which serves as a positive rake surface.
And a sloped surface 9 rising from the groove bottom to the boss surface 5. Further, the breaker groove 6 at the corner portion extends radially from the boss surface 5 toward each corner and has a projection 10 whose height gradually decreases at the tip. and the part thereof is disposed intermediate the projection 10 is formed by combination of at least one spherical projection 11 projecting from both sides, the main cutting angle of inclination theta ₂ of the inclined surface 8 of the corner A throw-away tip characterized by being formed to be smaller than the inclination angle θ ₁ of the inclined surface 8 in the blade portion. 2. The throw-away tip according to claim 1, wherein the land 7 provided in the breaker groove 6 is provided only in the main cutting edge portion and not in the corner portion.