JP4540764B2 - Cutting tools - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cutting edge-exchangeable cutting tool having an arc cutting edge used for engraving a mold, for example.
[0002]
[Prior art]
A radius end mill shown in FIG. 5 is known as an example of a cutting edge exchange type cutting tool provided with an arc cutting edge. The tool body has a cylindrical shape and is composed of a shank portion and a blade portion 21, and a tip mounting seat 22 that is opened outwardly in the rotational direction and the radial direction is formed on the outer periphery of the blade portion 21. Yes. A disc-shaped throw-away tip (hereinafter referred to as “chip”) 23 made of cemented carbide or other hard material is fastened to the tip mounting seat 22 by a tightening screw 25 using its central mounting hole 24. It is fixed. The chip 23 is incorporated so that the circular upper surface 26 is a rake surface and the annular side surface is a flank surface. The cutting edge 27 is formed at the intersection ridge line portion of the rake face and the flank face.
[0003]
The cutting tool having such a configuration has an advantage that the strength of the corner blade is increased, so that chipping and chipping are prevented, and in particular, it exhibits excellent performance in processing of a hard material and difficult-to-cut material. Further, when machining with a shallow cut, machining can be performed with high efficiency by increasing the feed amount per tooth without reducing the roughness of the machined surface. Furthermore, it is effective in preventing chatter vibrations in deep engraving with a long tool protrusion.
[0004]
[Problems to be solved by the invention]
Here, the problems of the prior art are described below.
[0005]
When cutting with a shallow incision in the axial direction of the tool body, the groove is gradually deepened by repeatedly cutting the same part, thereby increasing the contact area of the arc cutting edge and increasing the cutting resistance. Become. This occurs because there is no gap, so-called escape, between the outer peripheral blade and the wall surface of the machining groove. When the cutting resistance increases, vibration is induced, and chipping and chipping are likely to occur. That is, the increase in cutting resistance has a problem that the tool life is shortened and the roughness of the machined surface is lowered.
[0006]
[Means for Solving the Problems]
The present invention has been made in view of the problems as described above, and a plurality of throw-away tips are disposed on the outer periphery of the tip of the tool body having a columnar shape or a disk shape, and the upper surface thereof is directed in the rotation direction of the tool body. In the cutting tool that is detachably fixed to the tip mounting seat with a tightening screw by using each central mounting hole, the throw-away tip is made of a substantially triangular flat plate shape or a substantially rectangular flat plate shape. The cutting edge formed at the crossing ridge line portion between the upper surface and the side surface is a bottom blade and a corner blade arranged adjacent to each other with different radii of curvature, and a straight line arranged adjacent to the corner blade. The corner blade is a cutting blade that is located on the radially outer side of the tool body and cuts a portion corresponding to the machining diameter, and the bottom blade is a radius of the corner blade. In direction Adjacent to, the inner inclined to face the rear side toward the outer peripheral edge from the circumferential edge, a cutting edge responsible for cuts in working engraved with the corner cutting edge, the radius of curvature R1 of the bottom blade, the It is set to a dimension larger than the diameter of the inscribed circle or the length of the long side of the throw-away tip and set to a dimension larger than the radius of curvature R2 of the corner blade, and the cutting edge ridge line of the outer peripheral edge is the axis of the tool body It is arranged at an angle α with respect to the direction.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A tool body 1 shown in FIGS. 1 and 2 has a cylindrical shape, and includes a shank portion 2 held by a machine tool and a blade portion 3 into which a chip 5 is incorporated. On the outer peripheral side surface of the distal end of the blade portion 3, a tip mounting seat 4 that is opened and cut out to the distal end side and the radially outer side of the tool body 1 is formed at a rotationally symmetric position. A chip 5 shown in FIG. 3 is fastened and fixed to the chip mounting seat 4 by a tightening screw 8 through a central mounting hole 7.
[0008]
As shown in FIG. 3, the chip 5 has a flat plate shape including a side surface 9 curved in a convex shape, and a substantially triangular flat upper surface 10 and lower surface 11. When the chip 5 is disposed on the chip mounting seat 4, the upper surface 10 forms a rake face, and the side surface 9 forms a flank face. At the intersecting ridge line portion between the upper surface 10 and the side surface 9, a bottom blade 6a and a corner blade 6b made of an arcuate ridge line and an outer peripheral blade 6c made of a straight ridge line are formed.
[0009]
The bottom blade 6a is a cutting blade that cuts the bottom surface of the workpiece, and the shape of the cutting blade affects the roughness of the processing surface and the processing efficiency. As the radius of curvature is larger, the roughness of the processed surface is improved 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 tip 5, the machining surface roughness is improved and the machining efficiency is increased. Next, the corner blade 6b adjacent to the bottom blade 6a is a cutting blade located on the outer side in the radial direction, and is also a cutting blade that cuts a portion corresponding to the machining diameter. That is, when the tool body 1 is fed in a direction perpendicular to the axis, the cutting edge that first contacts the workpiece is the corner blade 6b. For this reason, the corner blade 6b has both sharpness and cutting edge strength. Performance is required. However, the corner blade 6b has an improved cutting edge strength as the radius of curvature R2 increases, and an improved sharpness as the radius of curvature R2 decreases. Satisfying is not easy. 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 maintains both the sharpness of the triangular tip while maintaining the cutting edge strength of the so-called circular tip. It is comprised as follows.
[0010]
Next, the outer peripheral edge 6c adjacent to the corner edge 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 edge of the cutting edge forms a back taper α. Thus, the tool body 1 is formed so as to extend straight rearward in the axial direction. Here, the back taper means an angle inclined inward in the radial direction with respect to the axial direction of the tool body 1. As described above, the radius end mill having a circular insert has a problem that the contact area of the cutting edge 6 increases as the machining groove becomes deeper and the cutting resistance increases. Accordingly, the present invention is configured to form a relief in a state where the tip 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 machining can be achieved in the engraving process.
[0011]
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 is omitted. The main difference with respect to the first embodiment is the shape of the tip 12 used by being incorporated in the tool body. The tip 12 has a substantially rectangular shape, and an arc cutting edge that is a bottom edge 13a is formed on the ridge line portion on the long side. The radius of curvature R3 of the cutting edge is set to a dimension larger than the length of the long side of the chip. Although the above-described substantially triangular chip 5 can use three corners per chip, the present chip is different from the first embodiment in that two corners are used. Since this chip 12 can form the cutting edge ridgeline of the bottom edge 13a long, it is suitable for high-efficiency machining with high feed.
[0012]
The arrangement configuration of the bottom blade 13a, the corner blade 13b, and the outer peripheral blade 13c is the same as that of the substantially triangular tip 5 described above.
[0013]
【The invention's effect】
According to the present invention, smooth machining can be performed while suppressing an increase in cutting resistance during engraving. In addition, the feed amount can be increased and processing can be performed with high efficiency.
[Brief description of the drawings]
1A is a front view showing a first embodiment of a cutting tool according to the present invention, FIG. 1B is a side view, and FIG. 1C is a bottom view;
FIG. 2 is an enlarged view of the tip of a blade part in FIG.
3A is a front view and FIG. 3B is a side view of a tip used by being incorporated in the tool body of FIG. 1;
FIG. 4 is an enlarged view of the tip of a blade portion showing a second embodiment of a cutting tool according to the present invention.
FIG. 5 is an enlarged view of the tip of a blade portion showing an example of a conventional cutting tool.
[Explanation of symbols]
1 Tool body 5 Inserts 6a, 13a Bottom blades 6b, 13b Corner blades 6c, 13c Peripheral blades α Back taper R1, R3 Curvature radius of bottom blades R2, R4 Curvature radius of corner blades

Claims (1)

A plurality of throw-away tips are arranged on the outer periphery of the tip of the tool body having a columnar shape or a disk shape, with the upper surface thereof directed in the direction of rotation of the tool body. In the cutting tool that is detachably fixed to the tip mounting seat, the throw-away tip is formed of a substantially triangular flat plate shape or a substantially rectangular flat plate shape, and is formed at an intersection ridge line portion between the upper surface and the side surface thereof. The cutting edge is composed of a bottom blade and a corner blade arranged adjacent to each other with different radii of curvature, and an outer peripheral blade of a linear cutting blade arranged adjacent to the corner blade. , A cutting edge that is located on the radially outer side of the tool body and cuts a portion corresponding to the machining diameter, and the bottom blade is adjacent to the inner side in the radial direction of the corner blade and is directed from the inner peripheral edge toward the outer peripheral edge. After follow Inclined to travel toward a cutting edge responsible for cuts in working engraved with the corner cutting edge, the radius of curvature R1 of the end cutting edge is greater than the length of the diameter or long side of an inscribed circle of the cutting insert The dimension is set to a dimension larger than the radius of curvature R2 of the corner blade, and the cutting edge ridge line of the outer peripheral blade is disposed at an angle α with respect to the axial direction of the tool body. Cutting tool to do.

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