JPH08229709A - Throw away tip for grooving - Google Patents

Abstract

PURPOSE: To prevent the drop of the strength of a cutting edge used for a furtive groove machining of the corner part of a stepped round material. CONSTITUTION: The upper surface 2 of a throw away tip 1 has an outline shape formed by that a circular arc beyond a semicircle is projected from two sides facing each other of a square. An escape is given onto a peripheral surface 5 contacting to a circular arc shape cutting edge 4. The escape angle of the peripheral surface 5 is formed so that an escape angle β of the maximum width of the tip may be biggest and it is setting smaller gradually and continuously as it approaches to a tip and it may be the smallest escape angle β' at the tip part of the tip. Consequently, a conical body which is converged to an elliptical arc 7 toward a lower surface 6 is formed. Further, this conical body is formed up to the way approaching from the upper surface 2 to the lower surface 6 and a cylindrical body 9 is formed on this lower part. Additionally, a chanfering is applied in the lower surface 6 side so as to become wider gradually as it approaches from a tip end toward a rear end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away insert for grooving, which is used for grooving a corner of a stepped round bar.

[0002]

2. Description of the Related Art A throw-away tip 1 used for machining an arcuate groove in a corner of a work material 13 made of stepped round material as shown in FIG. 5 has a shape shown in FIG. The ones are the most common. The throw-away tip 1 has a constant clearance angle β of the peripheral surface 5 in contact with the arcuate cutting edge 4 and forms a cone extending from the upper surface 2 to the lower surface 6 at the cutting edge portion. Therefore, the tangent line of the peripheral surface 5 and the lower surface 6 draws an arc 14.

[0003]

In the machining of the corners, one side is end face grooving, so be careful of interference between the lower surface side of the grooving throw-away tip and the work material. It costs. In order to solve this problem, in the conventional throw-away tip as described above, a large clearance angle is set to avoid the interference on the side lower surface side, so that a large clearance angle is taken on the entire peripheral surface. Become. However, in reality, the clearance angle does not need to be so large on the tip side of the chip, because the interference problem is relatively small. On the contrary, the large clearance angle reduces the strength of the cutting edge, leading to a reduction in tool life.

[0004]

The present invention has been made in view of the above problems, and the upper surface of the throw-away tip for grooving of the present invention has an arc of more than a half circle from two opposite sides of a rectangular shape. A relief is provided at least on the peripheral surface of the cutting edge that has a protruding outer shape and that is formed by the ridgeline and that is in contact with the arc-shaped cutting edge. The clearance angle of the peripheral surface is the largest at the maximum width of the tip, becomes gradually smaller toward the tip, and becomes smallest at the tip of the tip. as a result,
The cutting edge portion forms a cone that converges into an elliptical arc toward the lower surface.

The cone may be formed from the upper surface to the middle thereof. A cylindrical body is formed in the lower portion, and in addition, the lower surface is chamfered so that the width gradually increases from the front end toward the rear end. Further, at least the arcuate cutting edge portion on the upper surface is provided with a step along the ridge line to form a breaker groove in which the arcuate cutting edge is lower than the upper surface. Alternatively, the breaker groove is formed by providing a concave groove having an arcuate cross section or an inclined surface whose rake angle is a regular angle along the ridgeline.

[0006]

With the above-described structure, the present invention avoids the interference problem and reduces the clearance angle on the tip end side to prevent the cutting edge strength from decreasing. This is because when the lower part of the cone is formed into a cylinder, the area of the lower surface of the chip is not smaller than that in the case where the lower surface is formed into a cone, and the lowering of the supporting force of the chip seat of the cutting tool is prevented. Furthermore, chamfering is added to the lower surface side in order to solve the interference problem newly caused by the cylindrical body. In this case, even if chamfering is added, the supporting area of the lower surface of the chip is larger than that of the whole cone.

The breaker groove on the upper surface is intended to improve chip control performance and reduce cutting resistance.

[0008]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, an upper surface 2 of a throw-away insert 1 for grooving has an outer shape in which an arc exceeding a semicircle projects from both short sides of a rectangle, and a cutting edge 3 formed by its ridgeline. At least the peripheral surface 5 in contact with the arcuate cutting edge 4 is provided with relief. The escape of the peripheral surface 5 is
There must be no interference with the work material. Therefore, the clearance angle β in the maximum width of the chip is the largest. The size is determined by the processing diameter, the chip height (the distance between the upper surface 2 and the lower surface 6), and the like.

By the way, in reality, since there is little interference problem on the tip side of the chip, a large clearance angle is not required in the relevant portion. Therefore, the present invention prevents the decrease in cutting edge strength by gradually and continuously decreasing the clearance angle as it approaches the tip. Then, it is formed so that the clearance angle β ′ is minimized at the tip of the tip, and as a result, a cone is formed so that the tangent line of the peripheral surface 5 and the lower surface 6 draws an elliptic arc 7 in a plan view. ing.

The above-mentioned grooving throw-away tip 1 is usually placed on a tip seat formed on a plate-like projection provided at the tip of a square rod-shaped bit shank, and is fixed by tightening with a presser foot component or the like. Has been used.

Next, another embodiment of the present invention is shown in FIGS. The shape of the cutting edge 3 forming the contour of the upper surface 2 of the throw-away tip 1 is the same as the above, but the upper surface 2
The arcuate cutting edge portion is provided with a step portion having a rake parallel to the upper surface 2 along the ridge line, and the breaker groove 8 is formed such that the arcuate cutting edge 4 is lower than the upper surface 2. . The breaker groove 8 is for promoting the chip curl by the stepped wall and improving the chip disposal performance. In addition, a step having a positive rake for reducing cutting resistance may be used.

The peripheral surface 5 of the throw-away tip 1 forms a cone that converges into an elliptical arc 7 up to the middle of the upper surface 2 and the lower surface 6, and the lower part thereof is a cylinder 9. Lower part is cylinder 9
Therefore, the area of the lower surface is increased and the supporting force of the tip seat of the cutting tool is strengthened. However, since it is feared that the problem of interference may occur again, chamfering 10 is performed on the lower surface side so that the width gradually increases from the tip end toward the rear end. By adding the chamfer 10, the area of the lower surface 6 can be made larger than that in the embodiment of FIG. 1 in which the entire peripheral surface 5 forms a cone.

The flat surface 11 is added to eliminate the step between the cylindrical body 9 and the chamfer 10. Also,
A V-shaped inclined surface 12 is formed on the lower surface 6 symmetrically with respect to the axis line so as to prevent lateral deviation against the cutting resistance when fixed to the cutting tool.

FIG. 4 shows still another embodiment, in which the same parts are designated by the same reference numerals. This grooving throw-away tip 1 differs from that of FIG. 2 only in the shape of the breaker groove 8. That is, the arcuate cutting edge 4 is on the same plane as the upper surface 2, and the breaker groove 8 is provided inside the arcuate cutting edge 4 leaving a minute land. As shown in FIG. 4B, the cross-sectional shape of the breaker groove 8 is such that it has an inclined surface that gradually lowers inward from the land and rises from the bottom to the upper surface 2. Further, it may have a cross-sectional shape formed by an arc-shaped curve.

[0016]

As described above, the indexable insert for grooving of the present invention avoids the interference problem in the processing of the sloping groove at the corner of the stepped round material, and has a small clearance angle at the tip end side. The reduction of cutting edge strength can be prevented. Further, the area of the lower surface of the tip is not smaller than that of the conventional throw-away tip in which the entire peripheral surface is formed of a cone, and the reduction of the supporting force of the tip seat of the cutting tool can be prevented.
Furthermore, the breaker groove provided on the upper surface is effective in improving chip control performance and reducing cutting resistance.

[Brief description of drawings]

FIG. 1 shows one embodiment of the present invention, wherein (a) is a plan view,
(B) is a front view, (c) is a side view.

FIG. 2 shows another embodiment of the present invention, (a) is a plan view, (b) is a front view, (c) is a side view, and (d) is a bottom view.

FIG. 3 is a partial perspective view of the throw-away tip shown in FIG.

FIG. 4 is a partial view showing another embodiment of the present invention,
(A) is a plan view and (b) is a front view.

FIG. 5 is a conceptual diagram for explaining a processing state.

FIG. 6 shows a conventional example, (a) is a plan view,
(B) is a front view, (c) is a side view.

[Explanation of symbols]

 1 Throw-away tip 4 Arc-shaped cutting edge 5 Circumferential surface 7 Elliptical arc 8 Breaker groove 10 Chamfer β, β ′ Clearance angle

Claims (4)

[Claims] 1. The upper surface 2 which constitutes a rake face during cutting,
The cutting surface 3 of the cutting edge 3 formed by the ridgeline has an outer shape in which an arc exceeding a semicircle projects from two opposite sides of the square, and at least the peripheral surface 5 in contact with the arc-shaped cutting edge 4,
In the throw-away insert 1 for grooving provided with relief, the clearance angle of the peripheral surface 5 is the largest clearance angle β in the maximum width of the chip, and gradually decreases continuously as it approaches the tip, The grooved indexable insert is formed so that the clearance angle β ′ is minimized, and as a result, a cone is formed so as to converge to the elliptic arc 7 toward the lower surface. 2. The pyramid is formed partway from the upper surface 2 to the lower surface 6, and a cylindrical body 9 is formed in the lower part of the pyramid. In addition, the lower surface gradually increases from the front end toward the rear end. The indexable insert for grooving according to claim 1, wherein a chamfer 10 having a wide width is applied. 3. A step along the ridge line is provided on at least the arcuate cutting edge portion of the upper surface 2 so that the arcuate cutting edge 4 has the upper surface 2
The throw-away tip for grooving according to claim 1 or 2, wherein the breaker groove 8 at a lower position is formed. 4. A breaker groove 8 is formed on at least the arc-shaped cutting edge portion of the upper surface 2 by providing a concave groove having an inclined surface or an arc-shaped cross section whose rake angle is a regular angle along the ridgeline. The indexable insert for grooving according to claim 1 or 2.