JPS62807Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to an improvement of a throw-away tip that constitutes the center cutting edge of a throw-away type drill.

(b) Prior Art The present applicant has proposed a drill that eliminates the drawbacks of general throw-away drills by providing a chisel blade on the center blade of the throw-away drill, and a throw-away tip used for the center blade. This was proposed in Japanese Patent Application No. 54-53928.

As shown in FIGS. 1 and 2, the above-mentioned drill has a throw-away tip 3 attached to the tip of a main body 1 using a presser foot 2 whose axial position can be finely adjusted as a central cutting edge. Furthermore, the other throwaway tip 4 in contact with the tip 3 is used as an intermediate cutting edge, and the tip 5 on the opposite side of this tip is used as an outer peripheral cutting edge to make it possible to machine large diameter holes.
The trajectories of the front cutting edges of No. 5 are aligned on the same line with some overlap, so that no uncut material is left in the cutting area of the machined hole. On the other hand, the throw-away tip 3 used for the center blade has an upper surface 3a and a lower surface 3b parallel to each other, as shown in FIGS. 3 to 6.
and two opposing sides that intersect with the top surface at an angle of 90° or less 3
At least one of the acute angle corners of the chip, which is approximately rhombic in original shape, is cut out to a certain dimension, and this cutout is 3e, the intersecting line 3f of the two opposing sides at the obtuse corner is used as a chisel blade to improve the biting of the cutting blade into the workpiece, and at the same time reduce the thrust load during cutting. I'm keeping it small.

(b) Problems to be solved by the invention However, although the drill shown in Figure 1 has dramatically improved hole-machining efficiency compared to the general twist drill or throw-away type drill, it has a chisel blade. As with twist drills, this causes problems such as damage to the chisel blade and welding of chips to the tool.

On the other hand, a drilling tool that eliminates the chisel blade and solves the above problem by arranging a pair of chips with the starting end of the front cutting edge located near the center of rotation at the tip of the tool body symmetrically with respect to each other. For example, in 1983,
It has already been proposed by No. 80676. but,
If this technology were to be applied directly to an indexable drill, it would require two chips on the center blade whose trajectories are almost the same as the front cutting edge.
It will be economically disadvantageous.

(c) Means to solve the problems This invention aims to eliminate the problems mentioned above.
This is an improved throw-away chip shown in Figures 6 to 6, and its feature is that the intersection line at the obtuse corner between the two opposing sides and the other two opposing sides is partially chamfered on the top and bottom surfaces. This is removed by installing a groove at the center of the intersection line, and the intersection line between the two mutually independent opposing sides and the upper and lower surfaces is used as the center cutting edge of the drill.

(d) Embodiment An example of the throw-away tip of this invention is shown in the attached FIGS. 7 to 10.

The throw-away chip 10 shown in the figure is a positive type chip whose original shape including the dashed line part in FIG. It has side surfaces 13 and 14 and side surfaces 15 and 16 that intersect with the lower surface at an angle of 90° or less, and has an original acute corner 17,
18 is removed leaving an arbitrarily determined length from the center of the chip. In addition, the acute corner 17,1
At least one of the corners 8 must be removed to connect the intermediate blade, but the other corner may be left as is.

Next, in the above-mentioned conventional chip, the intersection lines of the side surfaces 3c, 3d and 3c', 3d' located at the obtuse corner portions were used as chisel blades, but in this invention, the side surfaces 13, 15 and 3d located at the obtuse corner portions were used as chisel blades. 14,1
6 to the upper surface 11 at the corner.
and by chamfering the lower surfaces 12 in the direction toward each other (chamfered portions 11a and 12a) and providing a groove 19 at the center of the intersection line, the side surface 13 is removed as shown in FIG. An intersection line 20 that touches the top and bottom surfaces and an intersection line 2 that touches the top and bottom surfaces of the side surface 15
1 are made independent of each other. In addition, chip 10
Since the rear view shape is the same as the front view shape of FIG. 7, the intersection lines 20' and 21' touching the upper and lower surfaces of the side surfaces 14 and 16 are similarly independent. In the right side view at this time, the upper and lower sides of FIG. 10 are reversed, and the side surface 14 appears at the position of the side surface 15 in the figure, and the side surface 16 appears at the position of the side surface 13.

Now, in the chip 10 constructed as described above, the intersection of the two opposing sides and the upper and lower surfaces is used as the center blade of the indexable drill, but the blades involved in cutting differ depending on the orientation of the chip. That is, the seventh
If the tip shown in the figure is moved in parallel and attached to the center of the drill body 1 as shown in FIGS. 12 and 13, the intersection line 20 of the side surface 13, especially the 10
A portion from a point o to a point p in the figure and a portion near the groove 19 on the intersection line 21 contribute to cutting. on the other hand,
The chip in Figure 7 is centered around the diagonal line of the obtuse corner.
When it is rotated 180 degrees, translated in parallel, and installed at the center of the drill as shown in Fig. 12, the part of the intersection line 21 mainly from point o' to point p' and the part of the intersection line 20 located near the groove 19 are the cutting edges. becomes.

Furthermore, when the tip attached to the tip of the drill as described above is rotated 180 degrees around the diagonal line of the acute corner, the intersection lines 20' and 2 of the side surfaces 14 and 16 are
1' replaces the intersection lines 20 and 21 and becomes a cutting edge.

Note that each cutting edge (intersection line) near the groove 19 is the 10th
As shown in the figure, it is preferable to make the side view shape into a circular arc shape, or to form a shape close to a circular arc by connecting a large number of straight lines as shown in Figure 11. In this way, the cutting resistance is small. This also improves cutting and ejection performance.

In addition, a breaker groove 22 can be provided at a portion that becomes the rake surface of the chip to properly dispose of chips.

(e) Effects As explained above, the throw-away chip of this invention is designed by forming a groove in the center of the intersection line and a groove in the center of the intersection line between the two opposing side surfaces and the other two opposing side surfaces at the obtuse angle corner. By chamfering a portion of the chisel blade and using the intersecting line between the two opposing sides and the upper and lower surfaces as the center blade of the drill, there is no possibility of damage to the chisel blade or of chips entering the drill. Welding problems do not occur and thrust loads are also reduced.

Furthermore, since the center cutting edge of the drill can be formed with one chip, it is economically advantageous.

Furthermore, when the cutting edge near the groove is shaped into an arc or a shape close to it, the cutting resistance is small and the evacuation of cutting is also improved, so that the hole processing efficiency is further improved.

[Brief explanation of the drawing]

FIG. 1 is a front view of a conventional drill, FIG. 2 is an end view thereof, FIG. 3 is a front view of a conventional tip, FIG. 6 is a side view, FIG. 7 is a front view showing an example of the chip of this invention, and FIG. 8 is an improved C.
9 is a view as seen from direction D, FIG. 10 is a side view, and FIG. 11 is a side view of another embodiment.
FIG. 2 is a front view of a drill employing the chip of the present invention, and FIG. 13 is an end view thereof. 10...Throwaway chip, 11...Top surface, 12...Bottom surface, 13, 14...Two opposing sides,
15, 16...Other two opposing sides, 19...Groove, 2
0, 20', 21, 21'...intersecting lines.

Claims (1)

[Claims for Utility Model Registration] (1) Consisting of an upper surface and a lower surface that are parallel to each other, two opposing side surfaces that intersect with the upper surface at an angle of 90° or less, and two other opposing side surfaces that intersect with the lower surface at an angle of 90° or less; In a throwaway chip whose original shape is a rhombus with at least one acute corner cut off to an arbitrary dimension, the intersection line of the two opposing sides and the other two opposing sides at the obtuse corner is defined as the upper and lower surfaces at the corner. A throw-away tip characterized in that the intersection line between two mutually independent opposing sides and the upper and lower surfaces is used as the center cutting edge of a drill. (2) The throw-away tip according to claim 1, wherein the cutting edge (intersection line) near the groove is formed into a circular arc or a shape close to it.