JP2000308908A - Cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform smooth work by suppressing an increase of cutting resistance at work time of engraving. SOLUTION: A cutting edge of a throwaway tip 5 is constituted by end cutting/corner edges 6a, 6b having a mutually different radius of curvature to be adjacently arranged and an external peripheral edge 6c of a linear cutting edge adjacently arranged to the corner edge 6b. Further, radiuses of curvature R1, R2 of the end cutting edge 6a are formed in the dimension larger than a length of diameter or major side of an inscribed circle of the throwaway tip 5, and a cutting edge ridge line of the external peripheral edge 6c is arranged at an angle of α, relating to the axial direction of a tool main unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exchangeable cutting tool having an arcuate cutting edge used for, for example, engraving a die.

[0002]

2. Description of the Related Art A radius end mill shown in FIG. 5 is known as one example of a cutting tool having a cutting edge having an arc cutting edge. The tool body has a cylindrical shape, and includes a shank portion and a blade portion 21. On the outer periphery of the tip of the blade portion 21, there is formed a notched chip mounting seat 22 which is opened outward in the rotation direction and the radial direction. I have. A disc-shaped throw-away tip (hereinafter, referred to as “tip”) 23 made of cemented carbide or other hard material is tightened to the tip mounting seat 22 by a tightening screw 25 using a central mounting hole 24. Wearing is fixed. The chip 23 is incorporated so that the circular upper surface 26 is a rake face and the annular side face is a flank. The cutting edge 27 is formed at the intersection ridge line between the rake face and the flank face.

A cutting tool having such a structure has an advantage that chipping and chipping can be prevented because the strength of a corner blade is increased, and particularly, it exhibits excellent performance in processing hard materials and difficult-to-cut materials. I do. Further, when processing is performed with a shallow cut, the feed amount per blade can be increased and the processing can be performed with high efficiency without reducing the roughness of the processed surface. Further, it is effective in preventing chattering vibration from occurring in deep engraving with a long tool protrusion.

[0004]

Here, the problems of the prior art will be described below.

When cutting is performed by giving a shallow cut in the axial direction of the tool body, the groove is gradually deepened by repeatedly cutting the same portion, thereby increasing the contact area of the arc cutting edge and increasing the cutting resistance. Will be invited. This occurs because there is no clearance between the outer peripheral blade and the wall surface of the machining groove, that is, there is no escape. When the cutting resistance increases, vibration is induced, and chipping and chipping are likely to occur. That is, there is a problem that an increase in the cutting resistance shortens the tool life and lowers the roughness of the machined surface.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a plurality of indexable inserts are provided on a columnar or disk-shaped outer periphery of a tool body tip portion, and the upper surface thereof is provided with a tool. It is arranged facing the direction of rotation of the main body,
By using the respective center mounting holes, in a cutting tool that is detachably fixed to the chip mounting seat by a tightening screw, the indexable insert is formed of a substantially triangular flat plate shape or a substantially rectangular flat plate shape, The cutting edge formed at the intersection ridge portion between the upper surface and the side surface has a bottom blade and a corner blade which are arranged adjacently with different radii of curvature, and a linear cutting edge which is arranged adjacent to the corner blade. The radius of curvature of the bottom blade is set to a size larger than the diameter of the inscribed circle or the length of the long side of the indexable insert, and the cutting edge ridge line of the outer blade is the axis of the tool body. It is characterized by being arranged at an angle of α with respect to the direction.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The tool body 1 shown in FIGS. 1 and 2 has a columnar shape, and is composed of a shank portion 2 gripped by a machine tool and a blade portion 3 into which a tip 5 is incorporated. On the outer peripheral side surface of the tip of the blade portion 3, a chip mounting seat 4 which is opened and cut out on the tip side and the radially outer side of the tool body 1 is formed at a rotationally symmetric position. The tip 5 shown in FIG. 3 is fastened and fixed to the tip mounting seat 4 by a fastening screw 8 through the center mounting hole 7.

As shown in FIG. 3, the chip 5 has a convexly curved side surface 9 and a substantially triangular flat upper surface 10 and lower surface 1.
1 and a flat plate shape. When the chip 5 is placed on the chip mounting seat 4, the upper surface 10 forms a rake surface, and the side surface 9 forms a flank surface. At the intersection ridge portion between the upper surface 10 and the side surface 9, a bottom blade 6a and a corner blade 6b formed of an arc-shaped ridge and an outer peripheral blade 6c formed of a straight ridge are formed.

The bottom blade 6a is a cutting edge for cutting the bottom surface of a workpiece, and the shape of the cutting edge affects the roughness of the processing surface and the processing efficiency. As the radius of curvature increases, the roughness of the machined surface improves, and the feed amount per blade can be increased. Therefore, in the present invention, by setting the radius of curvature R1 of the bottom blade to be larger than the radius of the inscribed circle of the insert 5, the roughness of the machined surface is improved and the machining efficiency is increased. Next, the corner blade 6b adjacent to the bottom blade 6a is a cutting edge located on the outside in the radial direction, and is also a cutting edge for cutting a portion corresponding to a processing diameter. That is, the tool body 1
Is sent in the direction perpendicular to the axis, the cutting edge that comes into contact with the workpiece first is the corner blade 6b. Therefore, the corner blade 6b is required to have cutting performance of both sharpness and cutting edge strength. I have. However, the corner blade 6b improves the cutting edge strength as the radius of curvature R2 increases, while improving the sharpness as the radius of curvature R2 decreases. It is not easy to satisfy. Therefore, the present invention sets both the radius of curvature R2 of the corner blade 6b and the radius of curvature R1 of the bottom blade 6a to different dimensions, and has both the sharpness of a triangular tip and the sharpness of a triangular tip while maintaining the so-called cutting edge strength of a circular tip. It is configured as follows.

Next, an outer peripheral blade 6c adjacent to the corner blade 6b
Is a cutting edge for cutting the wall surface of the workpiece, and when the tip 5 is incorporated in the tool body 1, the cutting edge ridge forms a back taper α and extends straight rearward in the axial direction of the tool body 1. It is formed to exist. Here, the back taper refers to an angle inclined inward in the radial direction with respect to the axial direction of the tool main body 1. As described above, the radius end mill having the circular insert has a problem that the contact area of the cutting edge 6 increases and the cutting resistance increases as the processing groove becomes deeper. Therefore, the present invention is designed to form a clearance in a state where the chip 5 is incorporated in the tool body 1. Thereby, unnecessary interference between the outer peripheral blade 6c and the wall surface can be avoided, and thereby, smooth processing can be achieved in the engraving processing.

FIG. 4 shows a second embodiment of the present invention. The same components as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof will be omitted. The main difference from the first embodiment is the shape of the tip 12 used by being incorporated into the tool body. Chip 12
An arc-shaped cutting edge, which is a bottom edge 13a, is formed in a substantially rectangular shape, and a ridge portion on the long side thereof is formed. Radius of curvature R of cutting edge
3 is set to a size larger than the length of the long side of this chip. The above-described substantially triangular chip 5 can use three corners per chip, while the present chip also differs from the first embodiment in that it uses two corners. The present chip 12 is suitable for high-efficiency machining with high feed, because the cutting edge ridge of the bottom blade 13a can be formed long.

The arrangement of the bottom blade 13a, the corner blade 13b, and the outer peripheral blade 13c is the same as that of the above-described substantially triangular tip 5.

[0013]

According to the present invention, it is possible to carry out smooth machining by suppressing an increase in cutting resistance during engraving. Further, the processing can be performed with high efficiency by increasing the feed amount.

[Brief description of the drawings]

FIG. 1A is a front view, FIG. 1B is a side view, and FIG. 1C is a bottom view showing a first embodiment of a cutting tool according to the present invention.

FIG. 2 is an enlarged view of the tip of a blade portion of FIG. 1 (a).

3 (a) is a front view and FIG. 3 (b) is a side view of a chip incorporated and used in the tool main body of FIG.

FIG. 4 is an enlarged view of a tip of a blade portion showing a second embodiment of the cutting tool according to the present invention.

FIG. 5 is an enlarged view of a tip of a blade portion showing an example of a conventional cutting tool.

[Explanation of symbols]

 1 Tool body 5 Tip 6a, 13a Bottom blade 6b, 13b Corner blade 6c, 13c Outer edge α Back taper R1, R3 Curvature radius of bottom blade R2, R4 Curvature radius of corner blade

Claims (1)

[Claims] 1. A plurality of indexable inserts are arranged on the outer periphery of a cylindrical or disc-shaped tool body tip with its upper surface directed in the direction of rotation of the tool body, and each of the center mounting holes is used. A cutting tool, which is detachably fixed to a tip mounting seat with a tightening screw, wherein the throw-away tip is formed in a substantially triangular flat plate shape or a substantially rectangular flat plate shape, and an intersection ridge line between an upper surface and a side surface thereof. The cutting edge formed in the portion is composed of a bottom blade and a corner blade which are arranged adjacent to each other with different radii of curvature, and an outer peripheral blade of a linear cutting edge arranged adjacent to the corner blade. The radius of curvature of the bottom blade is set to a size larger than the diameter of the inscribed circle of the throw-away tip or the length of the long side, and the cutting edge ridge of the outer peripheral blade is at an angle α with respect to the axial direction of the tool body. Arranged Cutting tool, characterized in that.