JPH10100013A - Cutting insert and cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an economical cutting insert and a cutting tool which can well cut a work near the central axis thereof even if they are used at a high insert position and can be used for cutting at not less than three corners. SOLUTION: Each cutting edge 2 of a polygonal insert 1 is recessed in the whole length and the lowest point 4 is made at a position 3/5 to 9/10 of the cutting edge length. The insert 1 is mounted on a tool body 11 such that the bottom cutting edge 2 toward the tip end side of the insert 1 intersects or comes near the central axis 12 of the tool body 11 at the part spaced from the lowest point 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polygonal cutting insert used for processing a metal material and the like, and a cutting tool having a cutting insert mounted on a tip end thereof.

[0002]

2. Description of the Related Art In order to cut a metal material or the like, a cutting tool has been used in which a cutting insert having a cutting edge formed on an upper ridge is detachably mounted on a tip of a cylindrical tool body. Was.

In such a cutting tool c, as shown in the front view of FIG. 6, a sufficient thickness t under the bottom surface of the cutting insert d is ensured to secure the strength of the tip of the tool body c1. The fixing position of the cutting insert d has been slightly increased to make the center height higher.

However, when the cutting insert d is mounted at the center height, there are the following problems. That is, when the center height is set, the distance between the bottom cutting edge d1 and the central axis c2 of the tool main body c1 increases. In the case of machining using the bottom cutting edge d1, the bottom cutting edge d1 is located very near the center axis c of the tool body c1.
An area S that cannot be cut by itself is created, and as a result, this area generates a large frictional force between the flank d2 of the bottom cutting edge d1 and the work material. JP-A-6-155127 solves the above problem. Therefore, the cutting edge D1 as shown in the front view of FIG.
An insert D having a concave portion D3 formed in a very narrow range is used, and the cutting blade D1 having the concave portion D3 is replaced with a bottom blade D1.
And the lowermost point of the concave portion D3 intersects or approaches the center axis C2 of the tool main body C1 so that the above-described problem does not easily occur even when the center height is increased. The cutting insert D has a parallelogram shape with long sides and short sides as shown in the top view of FIG. 8, and only two short sides of the cutting insert D have a bottom cutting edge D1 formed with the concave portion D3. As shown in the side view of FIG. 9, the long side D4 is a one-sided straight cutting edge D4 dedicated to the side edge, so that only two cutting edges (D4, D4) can be used as the side edge. It had two corners.

[0005]

However, the above prior art has the following problems. First, the cutting insert D in which the cutting edge D1 is provided with the concave portion D3 has a number of corners of 2
There was a problem that it was not economical.

Although the concave portion D3 is formed in a very narrow range in the bottom cutting blades D1 and D1 dedicated to the bottom blade, it has a curved shape with a small radius of curvature (a sharp change in direction).
The strength was low, and there was a possibility that chip discharge might be irregular or clogged.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention can cut the vicinity of the center axis of a cutting tool well even when used at a center height, and can be used at three or more corners, thus being economical. It is an object to provide a simple cutting insert and a cutting tool.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a polygonal insert in which the entire length of each cutting edge is concave, and the lowermost point of the cutting edge is 3 mm of the cutting edge length from the far end. /
The position was 5 to 9/10. Further, the cutting insert was attached to the tool main body such that the bottom cutting edge directed to the tip side of the cutting insert intersected or approached the center axis of the tool main body at a portion spaced from the lowermost point.

[0009]

In the polygonal insert of the present invention, each cutting edge is concave. Therefore, when the cutting blade is used as the bottom blade, by setting the cutting blade so as to intersect or be close to the center axis of the tool body at a position lower than the nose portion, the center of the cutting tool can be used even at the center height. The vicinity of the shaft is also cut well with a cutting blade.

[0010] In addition, since each of the above-mentioned cutting edges has a concave shape and does not have a curved portion having a small radius of curvature (a sharp change in direction), the edge strength is large even when used as a bottom cutting edge.

Further, since the same gentle cutting edge as a whole can also be used as a side cutting edge, it is economical to use three or more corners. The high rake portion having a low cutting resistance corresponds to the interval from the nose portion at one end of the cutting edge to the lowest point.

Therefore, it is preferable that the lowermost point of the cutting edge is as far as possible from the nose portion at one end and as close as possible to the other end, but when used as a bottom cutting edge, a sharp change in the shape and direction of the cutting edge occurs. The lowermost point is preferably located 3/5 to 9/10 from the far end of the entire length of the cutting blade so that the cutting edge strength does not decrease and the chip discharge direction does not become unstable.

Further, the cutting edge having a concave length has a shape gradually depressed inward from the nose portion to the lowermost point in a top view, and when the insert is installed with an axial rake at a center height, the verticality is reduced. Work extremely high.

Next, the cutting tool according to the present invention has a cutting insert attached such that the bottom cutting edge intersects or approaches the center axis of the tool body at a portion spaced from the lowest point. In the vicinity of the central axis, the bottom cutting edge is substantially point-symmetric with respect to the central axis.

Such an arrangement of the cutting blades has a good balance,
Since the direction of the cutting resistance is not biased and the chips are smoothly discharged without forcibly bending in the width direction, the chip dischargeability is high.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1 and 2 show plan views of a cutting insert (hereinafter abbreviated as “insert”) 1 of the present embodiment. This polygonal insert 1 has a cutting edge 2 formed on an upper edge and a side surface shown in FIG. As shown in the figure, each cutting edge 2 is formed in a concave shape.

Each of the cutting edges 2 has the same height of the nose portions 3, 3 at both ends of the cutting edge 2, and gradually from each nose portion 3 toward the lowest point 4 between the nose portions 3, 3. Nose part 3 which is formed so as to be lowered and whose lowermost point is farther
From 3/5 to 9/10 (y / x) of the cutting blade length. The insert 1 is configured such that the plan view of each side surface is exactly the same as the side view of FIG. Also,
As shown in FIG. 1, the cutting blade 2 appears as a concave shape in which the lowermost point 4 is the innermost in the top view.

Next, FIG. 3 and FIG.
FIG. 3 shows a cutting tool 10 equipped with a cutting tool, and FIG.
Is a side view.

As shown in FIG. 3, the bottom cutting edge 2 of the insert 1 is positioned at the lowest point 4 with respect to the center axis 12 of the tool body 11.
The insert 1 is mounted at a center height so as to intersect or be very close at a more spaced portion. Further, as shown in the side view of FIG. 4, the insert 1 is attached with an axial rake, and the insert 1 is provided with a concave cutting edge 2 having the lowermost point 4 as the innermost side (see FIG. 1). As shown in the schematic diagram of the processing surface of FIG.

In the above cutting tool 10, since the bottom cutting edge 2 is installed at a position lower than the nose portion 3 so as to intersect or be close to the center axis 12 of the tool body 11, the center of the tool body 11 can be used even when used at a center height. The vicinity of the shaft 12 is also satisfactorily cut with the bottom cutting edge. Moreover, the bottom cutting edge 2 is positioned near the central axis 12 near the central axis 12.
, And the cutting edge 2 does not have a sharp curve, so that the cutting resistance at this portion is small and the flow of the chips is good, so that the strength is high.

Further, since each of the cutting edges 2 has a concave shape and does not have a curved portion having a small radius of curvature (a sharp change in direction), the cutting edge 2 has a high cutting edge strength even when used as the bottom cutting edge 2.

Furthermore, each cutting edge 2 has the same shape and is used as both a bottom cutting edge and a side cutting edge. Therefore, three or more corners can be used as side cutting edges, which is economical.

The maximum of the high rake portion n having a low cutting resistance is the interval from the tip (bottom) nose portion 3 to the lowest point 4. Therefore, it is preferable that the lowest point 4 of the cutting edge 2 is as far as possible from the far nose portion 3 and as close as possible to the other nose portion 3. Considering that with certain cutting blades, the edge strength decreases and the chip discharge direction becomes unstable,
The lowest point 4 was set at a position 3/5 to 9/10 of the entire length from the nose portion 3 far from the cutting blade 2.

If the lowermost point 4 of the cutting edge 2 is located at a position closer than 3/5 of the entire length from the nose portion 3 which is farther away, the high rake portion n becomes smaller, so that the machining efficiency becomes worse. If it is more than 9/10,
It is necessary to provide a sharply curved portion near the lowermost point because the nose portion 3 is too close to the other nose portion 3, and since the amount of change in the direction of the cutting edge 2 is large, the cutting edge strength when used as a bottom cutting edge decreases,
Alternatively, the direction in which the chips are discharged may be unstable.

[0025]

As described above, according to the present invention, in the polygonal insert, each cutting edge has the same shape without any sharply curved portion and the entire length is concave, so that the cutting edge is used as the bottom cutting edge. However, the vicinity of the center axis of the tool main body is also satisfactorily machined, the cutting edge strength is high, the chip discharging property is good, and the constituent cutting edge is hardly generated. In addition, since this cutting edge can be used as a side cutting edge, it can cope with machining accompanied by cutting of the bottom surface, and can be used economically because three or more corners can be used as a side cutting edge. Further, the insert of the present invention can be processed with a very high verticality.

Next, the cutting tool of the present invention is arranged so as to intersect or approach the center axis of the tool body at a portion spaced from the lowermost point of the concave bottom cutting edge, so that the cutting tool has good balance and has a low cutting resistance. Since the direction is not deviated and the chips are smoothly discharged without forcibly bending in the width direction, the chip dischargeability is good.

As described above, the present invention has an extremely excellent effect.

[Brief description of the drawings]

FIG. 1 is a top view of a cutting insert of the present invention.

FIG. 2 is a side view of the cutting insert of FIG. 1;

FIG. 3 is a front end view of the cutting tool of the present invention.

FIG. 4 is a side view of the cutting tool of FIG. 3;

FIG. 5 is a schematic cross-sectional view showing a machined surface by the cutting tool of FIG. 3;

FIG. 6 is a front end view of a conventional cutting tool.

FIG. 7 is a front end view of a conventional improved cutting tool.

FIG. 8 is a top view of the cutting tool of FIG. 7;

FIG. 9 is a side view of the cutting tool of FIG. 7;

[Description of Signs] 1 (Cutting) Insert 2 Cutting Edge (Bottom Cutting Edge, Side Cutting Edge) 3 Nose Part 4 Bottom Point 10 Cutting Tool 11 Tool Body 12 Center Axis y Distance from far nose to cutting edge x Overall length of cutting edge n High rake

Claims (2)

[Claims] 1. A polygonal plate having a cutting edge formed on each ridge of each side of the upper surface. Each of the cutting edges has a concave shape, and its lowermost point is cut from a far end. 3 / of blade length
A cutting insert, which is located at a position of 5 to 9/10. 2. A cutting tool in which a cutting insert of a polygonal plate-like body having a cutting edge formed on a ridge of each side of an upper surface is fixedly held at a tip portion of a cylindrical tool body. A cutting tool characterized in that a concave bottom cutting edge directed to the side intersects or approaches the central axis of the tool body at a portion spaced from its lowermost point.