JPS6023926B2 - Throw-away drilling tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drilling tool having a cutting edge that is indexable.

As is well known, the conventionally commonly used drilling tools are:
A twist drill (hereinafter referred to as a drill) as shown in FIGS. 1 and 2 is comprised of a shank portion 2, a body portion 3, and a tip portion 4 at the tip of the body portion 3.

The tip 4 is provided with a predetermined tip angle 5, and a cutting edge 6, a core cutting edge 7, and a margin 8 serving as a guide are formed here, and from the tip 4 to the body 3, each of the above-mentioned points is formed. A helical groove 9 for discharging chips is formed corresponding to the cutting edge 6. As is clear from the shape of this type of drill, all parts are integrally formed, so if the cutting edge line 6 becomes worn, it will be necessary to re-grind it. , equipment, personnel, etc. are required, which limits the reduction in product manufacturing costs including tool costs, and on top of that, differences in re-grinding techniques can cause large changes in cutting performance. Furthermore, as is well known, when drilling a hole, the cutting speed at the center of rotation and the cutting speed at the peripheral green portion are significantly different, with substantial cutting not being performed at the chisel portion and the cutting speed becoming faster at the peripheral edge. Therefore, in the conventional drill 1 as described above, since all parts are made of the same material, each part of the cutting edge 6 and the core cutting edge 7 have different degrees of wear and tear, and even if the center of rotation of the cutting edge 6 Even if the side portion or the core cutting edge 7 is still usable, the circumferential ridge of the cutting edge 6 will wear out, resulting in markedly poor drilling accuracy and chip evacuation performance, or when using large diameter Drilling has very poor processing efficiency, causing problems such as increased thrust in the scale direction, and increasing the thrust causes wear and loss of sharpness of the chisel, shortening its life. Problems such as whether or not this occurs also arise. Furthermore, conventional drills have limitations in drilling accuracy and chip evacuation ability.
Depending on the tool material, there are limits to chip conditions such as feed rate and hole depth, and there are limits to improving overall machining performance. These problems, in turn, are a major obstacle in improving the efficiency of manufacturing operations. The present invention was made in view of the above circumstances, and aims to improve the cutting performance of a drilling tool.The present invention is characterized by two polygonal negative throw-aways at the tip of the drill body. The point is that the chips are arranged in a specific relationship.

Embodiments of the present invention will be described below with reference to FIGS. 3 to 7. The drill body 10 is formed into a solid shaft with a pointed tip angle of nearly 180 degrees, and the tip is notched in two places along the wisteria line direction, and a chip discharge groove is formed in the tip. 11 and 12 are formed. A chip mounting seat 13 is formed on the rotation center o side of a surface 11a facing the rotational direction A of the drill body 10 among the surfaces surrounding one of the cutting discharge grooves 11, and a chip mounting seat 13 is formed on the surface surrounding the other cutting shoulder discharge groove 12. A tip mounting seat 14 is formed on the peripheral side of the surface 12a of the drill body 10 facing in the rotational direction A. The drill body 101 also includes a cooling lubricant supply section (not shown) at the rear end.
2 which passes through the lotus and opens into each of the chip discharge grooves 11 and 12.
Two pipe lines 15 and 16 are formed, and each pipe line 15
, 16, a cutting agent such as a coolant and a lubricant can be supplied to the tip of the drill body 10, that is, the cutting portion. A central cutting edge tip 17 is mounted on the tip mounting seat 13 and fixed with a clamp piece 18 and a clamp screw 19.
An outer peripheral cutting edge tip 20 is fixed to the clamp piece 21 by a clamp piece 21 and a clamp screw 22. Each of these chips 17, 2
0 has twice the cutting edge line compared to the positive tip,
Therefore, in consideration of the possibility of reducing the running cost of the drill, a negative tip is used, and the shape in plan view is formed into a polygonal shape such as a square.
These are fixed in the states shown in FIGS. 5 to 7. That is, FIG. 6 shows the fixed state of the central cutting edge tip 17. In this figure, the x-X line indicates the rotation center axis of the drill body 10, and the Y-Y line indicates the rotation center ○ and the x-X line. The figure shows a plane perpendicular to the line, and the center cutting edge tip 17 has one end P of the full-length cutting edge 17a coincident with the rotation center 0, and the full-length cutting edge 17a extends from the rotation center 0 side toward the outer circumferential side. Therefore, an angle corresponding to the cutting angle is set with a 0 degree inclination from the tip side to the rear side of the drill body 10, and furthermore, the cutting edge line 17a
The circumferential side surface 17b constituting the blade is tilted rearward by Q degrees with respect to the plane of rotation of the cutting edge 17a centered on the X-X line (○'-Q plane in Fig. 5), which corresponds to the clearance angle. It is fixed so that the angle is set. therefore,
The actual tip angle of the drilling tool to which the central cutting tip 17 is attached is (180 - 28) degrees, and the central cutting tip 17 is attached to the workpiece only by the cutting edge 17a. will be in contact with. On the other hand, the outer cutting edge 20a of the cutting edge 20a on which cutting is to be performed is parallel to the rotational surface of the drill body 10, and its inner peripheral portion protrudes toward the rotation direction A side with respect to the radial line passing through the rotation center ○. Further, the circumferential side surface 20b constituting the entire blade ridge line 20a is inclined at a predetermined angle rearward with respect to the rotating surface of the blade ridge line 20a, and as shown in FIG. The inner circumferential end of the straight line portion 20a intersects with the outer circumferential end of the straight line portion of the cutting edge 17a of the central cutting edge tip 17 in the rotation locus. Therefore, the outer circumferential cutting edge tip 20 contacts the workpiece only at the cutting edge line 20a, and the other ridgelines or corners do not contact the workpiece. By the way, if the central cutting edge tip 17 is arranged alone,
Since it is a negative chip, the point M located diagonally to the point P in Fig. 6 protrudes to the outer circumferential side from the cutting edge ridge 17a, and the part near the point M interferes with the workpiece. do. Similarly, when the outer cutting edge tip 20 is placed alone, the area around the point indicated by the symbol N in FIG. 6 interferes with the workpiece. Therefore, in the drill of the present invention, the straight line portion of the cutting edge line 17a of the center cutting edge tip 17 and the straight line portion of the cutting edge line 20a of the outer peripheral cutting edge tip 20 are made to intersect, thereby forming the points M and N. Interference with the workpiece in the vicinity of each part is prevented.

That is, when the straight line portions of the cutting edge lines 17a and 20a intersect with each other as described above, point M is located in the area cut by the cutting edge line 20a, and point N' is located in the area cut by the cutting edge line 17a. It will be located in the area.
Therefore, the part near the point M''N will not interfere with the workpiece.In addition, regarding the interference with the workpiece near the points M and N, one of the center cutting edge tip and the outer peripheral cutting tip This can also be prevented even if the straight line part of one crosses the other circular arc part (nose part) or the circular arc parts cross each other.

However, in this case, the circular arc portion cuts the workpiece. However, in straight sections, the relief angle is approximately the same as the inclination angle of the tip with respect to the axis (axial rake angle), but in arcuate sections, the relief angle gradually decreases as the distance from the straight section increases. . For this reason, when attempting to perform high-feed drilling, the thrust load increases, resulting in a problem that high-feed drilling becomes impossible. However, in the above-mentioned basic drilling tool, if either or both of the tips 17 and 20 are worn out, it is only necessary to replace them, and the tips used are generally commercially available slow drills. An away chip is fine.

Also, use a throw-away tip with a breaker, or
Alternatively, if a cutter piece is used in combination, the chips can be cut to an appropriate length, making the process for discharging the chips easier. Incidentally, during cutting, the cutting agent is supplied through the pipes 15 and 16, and the center cutting tip 17 and the outer peripheral cutting tip 20 should be suitable for the cutting conditions. This eliminates the need to supply high pressure and large amounts of cutting fluid, and the cutting fluid used for cooling and lubrication is sufficient. In addition, in the above embodiment, the cross-sectional shape is approximately square.

Although an example using the away tips 17 and 20 has been described, the throwaway tip according to the present invention is not limited to having a substantially square cross-sectional shape as in the above embodiment, but may have a triangular shape as shown in FIG. 8, for example. Any commercially available throw-away tips, such as the throw-away tips 30 and 31, may be used. As explained above, according to the present invention, two indexable tips are removably attached to the tip of the drill body, so when the cutting edge wears out and its sharpness decreases, the indexable tip can be removed. All you have to do is replace the tip, and there is no need to re-grind the cutting edge like with conventional drills.

Therefore, equipment for re-grinding the cutting edge, which was previously required,
In addition to eliminating the need for personnel, a commercially available indexable tip can be used, and a drilling tool with uniform cutting performance can be obtained. In addition, if you use a cutter piece with an indexable insert or an indexable insert with a play force, it will be extremely easy to remove chips and prevent premature wear and chipping of the cutting edge. The chips constituting the central cutting edge can be made to suit the respective conditions such as cutting speed, and as a result, the life of the drilling tool as a whole can be extended, and the cutting power can be made smaller than that of the secondary tool. Furthermore, since the drilling tool according to the present invention requires relatively little thrust in all directions, it can be installed in conventional processing machines.
At the same time, multi-blade multi-tooling becomes possible, making the drilling process unmanned and labor-saving.

[Brief explanation of drawings]

Figure 1 is a side view of a conventional drill, Figure 2 is its front view,
Fig. 3 is a side view of essential parts showing one embodiment of the present invention, Fig. 4 is a front view thereof, Fig. 5 is an explanatory view showing the attachment state of the central cutting tip, Figs. 6 and 7. FIG. 8 is an explanatory diagram showing the relative positions of the center cutting edge tip and the outer peripheral cutting edge tip, and FIG. 8 is a side view of the main part showing another embodiment. 10... Drill body, 11, 12...
Chip discharge groove, 11a, 12a... (of each chip discharge groove) surface, 13, 14... Chip mounting seat, 17, 3
0...Central cutting edge tip, 17a...All blade ridgeline, 18, 21...Clamp piece, 20.3
1...Outer cutting edge tip, 20a...All blade ridgeline, 19, 22...Clamp screw, 0...
····Rotation center. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. Two polygonal negative throw-away tips are removably attached to predetermined locations on the tip of the drill body using clamp members, and chip discharge grooves are formed corresponding to the throw-away tips, so that the tip One end of the tip on the center side, where cutting is to be performed, coincides with the rotation center axis of the drill body, and as the tip goes from the inner circumferential side to the outer circumferential side, It is inclined toward the rear end side and is arranged at a predetermined angle with respect to the axial direction of the drill body so that a cutting edge clearance angle of a predetermined angle is formed with respect to the entire cutting edge line, and The inner edge of the straight part of the edge line of the tip that is to be cut intersects the outer edge of the straight part of the edge line of the tip on the inner circumference side in the rotation locus, and the edge of the tip on the outer circumference side The inner circumferential side of the full-length cutting edge line is inclined at a predetermined angle with respect to the radial direction so as to protrude in the rotational direction, and the cutting edge clearance angle is a predetermined angle with respect to the full-length cutting edge line in the axial direction of the drill body. A throw-away type drilling tool characterized by being arranged at a predetermined angle with respect to the drill.