JPH08252703A - Throw away tip - Google Patents

Abstract

PURPOSE: To improve roughness of the finish face of material to be cut and discharging disposal of chip. CONSTITUTION: The nose 9 of a throw away tip is formed out of a pair of subcutting blades 10a, 10b line symmetric against the bisector L of a pinch angle. The first cutting edge 12 of the subcutting blade 10a is formed into a circular arc, and when an intersection angle between a side 8 and the chord (k) of the first cutting edge 12 is set as θ and the length of the chord (k) as A, the radius R1 of the first cutting edge is obtained by R1 = (Atan θ)<2> +A<2> }/(2 Atanθ) or R1 =((Asinθ)<2> +A<2> }/(2Asinθ). A second cutting edge 13 continued to the first cutting edge 12 is formed into a circular arc of relative small diameter making the extension line of the chord (k) of the first cutting edge 12 as the tangent, and smoothly continued to it. A cutting edge 11 of small circular arc connects together a pair of the subcutting blades 10a, 10b between.

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 used for cutting a finished surface of a work material in milling, lathing and the like.

[0002]

2. Description of the Related Art Conventionally, as a throw-away tip formed in the shape of a polygonal plate, for example, there is a throw-away tip of a triangular plate shape having a nose with a sharp cutting edge as shown in FIG. Such throw-away tip 1
Each side 3 of the upper surface (and / or lower surface) 2 serves as a main cutting edge, and a nose 4 is formed between the two sides 3 and 3. In this case, the curve forming the nose 4 is, as shown in FIG.
An inscribed circle B having a radius R between the two sides 3 and 3 is constituted by a single arc starting from a contact point with each side 3.
When this throw-away tip 1 is attached to a lathe or the like and finish cutting of the machined surface of the work material W is performed, the feed direction of the tip 1 is indicated by an arrow P in FIG. The arc region 4a on the upper and lower sides serves as the main cutting edge, and the arc region 4a on the outer peripheral side (on the left side in the drawing) serves as the sub cutting edge, and cutting is performed.

[0003]

By the way, in this case,
When the nose R of the throw-away tip 1 is small, the cross section of the chip is short and the chip disposability is not bad, but the finished surface roughness of the machined surface is relatively small because the contact area with the machined surface of the work material W is relatively small. Has the drawback of becoming worse. On the other hand, if the nose R is large, the contact area with the work material W is expanded and the finished surface roughness is improved, but in the finish cutting with a small depth of cut, the arcuate area 4a forming the cutting edge of the nose 4 has the side 3 And a circle tangent to the inscribed circle B (extension line of side 3) m ′ are positioned so as to draw an arc in a direction away from each other. Therefore, the cross section of the chips generated in the cutting region 4a becomes close to an arc shape and the thickness of the chips becomes thin, so that the chips are less likely to curl and the chip handling property is poor.

In view of such circumstances, it is an object of the present invention to provide a throw-away tip capable of improving the chip disposability without impairing the finished surface roughness.

[0005]

The throw-away tip according to the present invention compares the radii of curvature of two sides connected to the nose, smoothly extending from the intersection with one side to the extension line of the side and extending inward. Large first convex curved cutting edge,
The second convex curved cutting edge having a relatively small radius of curvature whose tangent is the extension line of the chord connecting both ends of the first convex curved cutting edge from the end point of this first convex curved cutting edge is connected smoothly. A nose is formed by one sub-cutting edge that is present and the other sub-cutting edge that smoothly extends from the intersection of the other side to the inside of the extension line of that side and is connected to the one sub-cutting edge. It is characterized by that. The first convex curved cutting edge is located between the arc of the inscribed circle of the two sides connecting the two intersections and the extended line of the side. Further, the one sub-cutting edge and the other sub-cutting edge are formed in line symmetry with respect to the bisector of the included angle of the two sides. The first and second convex curved cutting edges are each formed in an arc shape. Also, the included angle of the two sides forming the nose is 90 degrees or less, and the intersection angle between the extension line of one side and the chord of the first convex curved cutting edge is θ, and the chord of the chord of the first convex curved cutting edge is When the length is A, the radius R1 of the first convex curved cutting edge is calculated by the following equation: R1 = {(Atan θ) ² + A ² } / (2Atan θ) or R1 = {(Asin θ) ² + A ² } / ( 2Asinθ) is set.

In addition, the throw-away tip according to the present invention is formed with a first convex curved cutting edge that smoothly extends from the intersection of one of the two sides connected to the nose to the extension line of that side. The sub-cutting edge of, and the other sub-cutting edge connected to the one sub-cutting edge extending smoothly from the intersection of the other side to the inside of the extension line of the side, the nose is formed,
In the first convex curved cutting edge, when the intersection angle between the extension line of one side and the chord of the first convex curved cutting edge is θ and the chord length of the first convex curved cutting edge is A, The radius R1 of the first convex curved cutting edge is set by the following formula R1 = {(Atan θ) ² + A ² } / (2A tanθ) or R1 = {(Asin θ) ² + A ² } / (2A sin θ) It is a feature. or,
A second convex curved cutting edge having a smaller radius of curvature than the first convex curved cutting edge may be provided at the connecting portion between the one sub cutting edge and the other sub cutting edge in the nose to be smoothly connected. .
Furthermore, in the throw-away tip described above, a small circular arc cutting edge having a diameter smaller than the diameter of the second convex curved cutting edge is provided at the connection portion of the one sub cutting edge and the other sub cutting edge in the nose. It may be connected smoothly. In addition, a pin angle apex may be formed at a connecting portion between one sub-cutting edge and the other sub-cutting edge.

[0007]

When performing the finish cutting of the work material with the nose of the throw-away tip having the above-mentioned structure, the first convex curved cutting edge of one of the sub cutting edges is more than the inscribed circle at the contact point (intersection point) with the side. Since it is a curve with a large radius of curvature, the finished surface roughness of the machined surface is good, and the cross section of the chips produced by this cutting edge is close to a straight line, so the thickness of the chips does not become too thin, so curling The cutting edge strength is improved because the second convex curved cutting edge is smoothly connected. Since the one sub-cutting edge and the other sub-cutting edge are line-symmetrical, it becomes a self-shaped tip,
Good finishing surface roughness and chip disposability can be obtained in cutting in any of the front, back, left and right directions. Also, since the first convex curved cutting edge becomes a curved line of a substantially arc close to the extension line of one side,
The finished surface roughness of the machined surface is even better.

Further, in the throw-away tip according to the present invention, when the finish cutting is performed by one of the sub cutting edges, the first convex curved cutting edge becomes a substantially circular arc curve which is close to the extension line of one side. The finished surface roughness of the machined surface is even better.
Further, if a small circular arc cutting blade is provided at the connecting portion of the one sub-cutting edge and the other sub-cutting edge in the nose, the cutting edge strength of the nose is high.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a first embodiment of the present invention. (A) is a plan view of a throw-away tip, (b) is a central longitudinal sectional view, and FIG. 2 is a nose of a throw-away tip shown in FIG. 1 (a). FIG. In FIG. 1, the throw-away tip 6 has, for example, a rhombus plate shape, and each side 8 of an upper surface (and / or lower surface) 7 thereof is a main cutting edge,
A pair of opposite corners forming an acute angle between the two sides 8 and 8 is a nose 9. Nose 9 shown in FIG.
Is composed of a pair of convex cutting edges 10a and 10b, respectively, on the bisector L of the included angle (blade angle: 90 ° or less, for example 80 °) of the two sides 8 and 8 connected to the nose 9. Connected by. The pair of sub cutting edges 10a and 10b are arranged symmetrically with respect to the bisector L. The connecting regions of the biconvex curved sub-cutting edges 10a and 10b are connected by a small arc-shaped cutting edge 11. Moreover, each of these cutting edges 10a, 10b, 11 forms a smooth curve as a whole.

Here, the sub-cutting edge 10a (10b) will be further described. An inscribed circle B between the two sides 8 and 8 (for example, the same diameter as the inscribed circle B in the prior art) is virtually drawn. , Starting from the contact point (intersection point) n1 of the one side 8 and the inscribed circle B, extending in the direction of the extension line m of the side 8 and curved in an arc shape with a radius R1 to inscribe the extension line m, and so on. The first cutting edge 12 is formed by terminating on the end point n2 close to the line L. The crossing angle between the chord k connecting the two points n1 and n2 of the first cutting blade 12 and the extension line m is θ (for example, θ = 4 °), and the length of the chord k of the first cutting blade 12 is A (for example, 1.0 mm), the radius R1 of the first cutting edge 12 is R1 = {(Atan θ) ² + A ² } / (2A tanθ) (1) or R1 = {(Asin θ) ² + A ² } / (2Asin θ ) (2) is set. The value of R1 is almost the same regardless of whether this equation (1) or equation (2) is used. For example, θ =
According to the equation (1) with A = 1.0 mm at 4 °, R1
= 7.185 mm, according to the equation (2), R1 = 7.20
It is 3 mm, which is about 7.194 mm on average.

On the side of the bisector L of the first blade 12, a point n2 is used as a starting point (contact point) and an extension line of the chord k is a tangent line with a radius R2 (for example, 0.4 mm, R2 <R1). Draw a short arc and make a radius R3 at point n3 (eg 0.2 mm, R3
The second cutting edge 13 is formed by connecting to the cutting edge 11 having a small arc of <R2. Moreover, the first cutting blade 12 and the second cutting blade 1
3 and the small arc cutting edge 11 form a smooth convex curve as a whole.

When θ = 4 ° and A = 1.2 mm, R1 = 8.622 mm in the equation (1) and R1 = 8.643 mm in the equation (2), which is about 8.63 mm on average. . The angle between the chords k of the pair of sub cutting edges 10a and 10b is, for example, 88 °. Also, in this case, n
The distance between 2-n3 is 0.01 mm, and the distance between n3-n4 is 0.2 mm, where n4 is the intersection of the extension lines of the pair of chords k.
The distance between n1 and n4 is 0.2 to 1.6 mm.

In the throw-away tip 6 having the nose 9 having the above-described structure, when performing the finish cutting of the workpiece W, it is assumed that the tip 6 is fed in the P direction in FIG. Finish cutting is mainly performed by the sub cutting edge 10a. In this case, the first cutting blade 12 has a diameter R
Since it is 1, which is considerably larger than the diameter of the inscribed circle B, the finished surface roughness is much improved and good compared to that of the above-mentioned prior art chip 1. Moreover, since the first cutting edge 12 for the machined surface of the work material W forms an arc closer to the extension line m of the side 8 than the arcuate cutting edge 4a of the prior art shown by the inscribed circle B, this cutting is performed. The cross section of the chips produced by the blade 12 is
The shape is closer to a straight line. Therefore, since the thickness of the chips does not become so thin, it becomes easy to curl neatly into a spiral shape and the processability of the chips becomes good. In the above description, the second cutting edge 13 is the first cutting edge 12 and the cutting edge 1 having a small arc.
Although it is provided between the first cutting edge 13 and the first cutting edge 13, the second cutting edge 13 need not have a short dimension, and in this case, the end point n of the first cutting edge 13 is n.
It is smoothly connected to the cutting edge 11 having a small arc from 2.

As described above, according to the present embodiment, the radius R1 of the first cutting edge 12 is considerably larger than the inscribed circle B of the nose and is close to the extension line m. An advantage that the roughness can be improved, and the cross-section of the chips generated by the first cutting blade 12 of the nose 7 becomes a shape closer to a straight line, and the chips can be easily curled neatly into a spiral shape to improve the processability. There is. Further, if the second cutting edge 13 is connected, the first cutting edge 12 is smoothly connected to the cutting edge 11 having a small arc, so the cutting edge strength is improved and the chip discharging property is also improved.
By providing the cutting edge 11 having a small arc, the cutting edge strength is further increased. Further, since the pair of sub cutting edges are formed line-symmetrically with respect to the bisector L, the throw-away tip has a non-selfish structure and is used for cutting in the front-rear and left-right directions, which is favorable. A finished surface roughness and chip disposability can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 3, a nose 9 is a pair of first blades 1.
2 and 12 and a pair of second cutting edges 13 and 13, only the small cutting edge 11 is not formed. Therefore, the second cutting edges 13, 13 intersect on the bisector L as a vertex (pin angle) 15. Even with such a configuration, an effect equivalent to that of the above-described embodiment that good surface roughness and chip disposability can be achieved is achieved.

In the above-mentioned embodiments and the like, the pair of axisymmetric first and second cutting edges 12 and 13 forming the nose 9 are circular arc-shaped cutting edges having a constant radius (R1, R2). However, it is not necessarily limited to a circular arc of a perfect circle, but the inside of each extension line m of the two sides 8 and 8 (and between the inscribed circle B) and the extension line m. The first convex curved cutting edge (12) and the second convex curved cutting edge (13) which are formed in close proximity to each other and are line-symmetrical. For example, an elliptic arc or a non-circular convex curve is formed. May be

The throw-away tip 6 according to the present invention
The shape is not limited to the rhombus plate shape, and may be an appropriate polygonal shape such as a trigonal plate shape as shown in FIG. 4 or a triangular plate shape, and at least one nose 9 is sufficient. Further, the included angle between the two sides connected to the nose 9 may exceed 90 °. In each of the above-mentioned embodiments, a breaker of any shape may be formed along the cutting edge on the rake face of the throw-away tip. At the time of forming the breaker, either grinding or molding may be used.

[0018]

As described above, in the throw-away insert according to the present invention, the finished convex surface roughness of the work material can be favorably maintained by the first convex curved cutting edge and the chips generated by this nose. Since the cross section of the chip has a shape close to a straight line, there is an advantage that the chips tend to curl neatly in a spiral shape and the processability is improved. Further, if the second convex curved cutting edge is provided, there is an advantage that the cutting edge strength and the chip discharging property are improved.

[Brief description of drawings]

FIG. 1 shows a throw-away tip according to a first embodiment of the present invention, (a) is a plan view and (b) is a central sectional view.

FIG. 2 is an enlarged plan view of the nose of the embodiment shown in FIG.

FIG. 3 shows a second embodiment of the present invention, and FIG.
FIG. 5 is an enlarged plan view of the nose similar to FIG.

4A and 4B are diagrams showing another shape of the throw-away tip to which the present invention is applied, FIG. 4A is a plan view, and FIG. 4B is a central sectional view.

FIG. 5 is a plan view of an example of a conventional throw-away tip.

FIG. 6 is an enlarged explanatory view of a nose in the throw-away tip shown in FIG.

[Explanation of symbols]

 8 sides 6 throw-away tip 9 nose 11 small arc cutting edge 12 first cutting edge 13 second cutting edge 15 apex

Claims (5)

[Claims] 1. A first convex curved cutting edge having a relatively large radius of curvature which extends smoothly from the intersection of two sides connected to the nose with one side to the extension line of the side and extends inward thereof.
The second convex curved cutting edge having a relatively small radius of curvature whose tangent is the extension line of the chord connecting both ends of the first convex curved cutting edge from the end point of this first convex curved cutting edge is connected smoothly. One sub-cutting edge that is, and the other sub-cutting edge that is connected to the second convex curved cutting edge that extends smoothly inside the extension line of the side from the intersection of the other side of the two sides, A throw-away tip that is formed with the nose. 2. The one sub-cutting edge and the other sub-cutting edge,
The throw-away tip according to claim 1, wherein the throw-away tip is formed in line symmetry with respect to a bisector of an angle between the two sides. 3. The first and second convex curved cutting edges are each formed in an arc shape.
Alternatively, the throw-away tip described in 2. 4. The included angle of the two sides forming the nose is 90 degrees or less, and the intersection angle between the extension line of the one side and the chord of the first convex curved cutting edge is θ, and the first convex When the length of the chord of the curved cutting edge is A, the radius R1 of the first convex curved cutting edge
4. The throw according to claim 3, wherein is set by the following formula: R1 = {(Atan θ) ² + A ² } / (2A tan θ) or R1 = {(A sin θ) ² + A ² } / (2A sin θ). Away tip. 5. One of the sub-cutting edges having a first convex curved cutting edge extending smoothly from the intersection of the two sides connected to the nose with the one side to the inside of the extension line of that side, and the other The nose is formed by the other sub-cutting edge that smoothly extends from the intersection with the side to the inside of the extension line of the side and is connected to the one sub-cutting edge, and the first convex curved cut When the blade has a crossing angle between the extension line of the one side and the chord of the first convex curved cutting edge as θ and the chord length of the first convex curved cutting edge as A, the first The radius R1 of the convex curved cutting edge is characterized by being set by the following equation R1 = {(Atan θ) ² + A ² } / (2A tanθ) or R1 = {(Asin θ) ² + A ² } / (2A sin θ) A throw-away tip to do.