JPS63114808A - Drill - Google Patents

Abstract

PURPOSE:To prevent chip packing from occurring, by setting each rake angle in the axial direction of two cutting edges of a drill to respective angles different with each other. CONSTITUTION:Two cutting edges 12 and 13 are formed in a tip part of a drill body, and two chip discharge grooves 14 and 15 corresponding to these two cutting edges 12 and 13 are formed on the periphery of the tip part. A tip part forming a rake angle of a wall surface of the chip discharge groove 14 on one side is cut down at a helix angle smaller than that on the other. Therefore, the rake angle in the axial direction of the cutting edge 12 on one side comes to a difference angle from that of the cutting edge 13 on the other. This angular difference should be a range of about 1 deg.-10 deg.. This gullet quantity is the largest at the outer circumferential part, gradually decreased toward the inner circumferential part, and coming to zero at a chisel part 18 in design. Accordingly, the required occupied space becomes narrowed as compared with chips by the conventional drill, thus the discahrgebility of chips is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a drill suitable for deep hole drilling.

[Prior art and its problems] In general, a drill has two cutting edges 2.2 formed at the tip of the drill body l, as shown in FIGS. 9(A) and (B), and each 2 with a twist corresponding to the cutting edge 2.2
It has a structure in which two chip discharge grooves 3, 3 are formed,
By setting the helix angles of the chip discharge grooves 3, 3 to be equal, the axial rake angles of the cutting edges 2.degree. 2 are made equal to each other.

By the way, when drilling is performed using the above drill, chips as shown in FIG. 1O are generated from each cutting edge 2.2. This chip is formed in a spiral shape around one imaginary axis, and requires a large space compared to the thickness and width of the board. For this reason, the problem of chip clogging is likely to occur, and this tendency is particularly noticeable when drilling deep holes, which may lead to the problem of drill breakage.

[Object of the Invention] This invention was made to solve the above-mentioned problems, and an object of the invention is to provide a drill with excellent chip evacuation properties.

[Means for Solving the Problems] In order to solve the above problems, the present invention is such that the rake angles in the axial direction of the two cutting edges are set to different angles from each other.

That is, as a result of intensive research by the inventor of this application, he came to the knowledge that when the rake angles of the two cutting edges in the axial direction are set to different angles from each other, chips as shown in FIG. 5 are generated. . The chips are ribbon-shaped and have a shape that is gently twisted around the center in the width direction. Unlike chips produced by conventional drills, which spiral around a single imaginary axis, this chip is twisted around its own midsection, occupying less space. It is narrower, and therefore chip evacuation is significantly improved compared to the conventional one.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 4. Note that FIG. 1 is a partially omitted side view showing a drill according to the present invention, and FIG. 2 is an enlarged view of the tip thereof.
FIG. 3 is a view taken in the direction of the ■ arrow in FIG.

The drill shown in these figures is a conventional drill that has been additionally machined in accordance with the technical idea of the present invention, and has two cutting edges 12 and 13 formed at the tip of the drill body 11. Further, on the outer periphery of the tip of the drill body 11, two
Two chip discharge grooves 14 corresponding to one cutting edge 12.13,
15 is formed. The helix angles of both chip discharge grooves 14, 15 are set to be equal to each other and θ1. Along these two chip evacuation iR14, l 5, the drill body ll
Margin portions 16 and 17 are formed on the outer periphery of.

The above configuration is the same as that of a conventional drill, but this drill has the following additional operations.

That is, the tip portion forming the rake surface of the wall surface of one of the chip discharge grooves 14 is cut off with a helix angle θ, which is smaller than the helix angle θ. As a result, the rake angle in the axial direction of one cutting edge 12 (the rake angle at the outer peripheral edge of the cutting edge 12) becomes θ2, and the rake angle of the other cutting edge 13 becomes θ1.
It's at a different angle. Regarding this angular difference, l
It is desirable to set it to 10°.

As is clear from FIG. 3, the amount of cut off is maximum at the outer periphery, gradually decreases from there toward the inner periphery, and reaches zero at a location in contact with the chisel portion 18.

When a hole is drilled with the drill configured as described above, chips as shown in Fig. 5 are generated not only from the cutting edge 12 having a small rake angle but also from the cutting edge 13 which has not undergone any additional machining. be done. As mentioned above, this chip has a loosely twisted shape centered on its center, and forms a spiral around an imaginary axis. Space becomes smaller. Therefore, the evacuation of chips is improved.

Next, other embodiments of the invention will be described.

In the following embodiments, the same parts as those in the above embodiments are given the same reference numerals, and the explanation thereof will be omitted.

Furthermore, it goes without saying that chips as shown in FIG. 5 are generated in the following examples.

The drill shown in FIGS. 6(A) and 6(B) has a solid carbide tip 19 whose cross-sectional shape is similar to that of the drill body 11, which is brazed to the tip of the drill body 11 made of steel. The rake face of one cutting edge 12 is machined in the same manner as in the above embodiment.

The drill shown in FIGS. 7(A) and 7(B') also has a plate-shaped cemented carbide tip 20 at the tip of the drill body 11.
．． 21 at an equal distance from the axis O (0.1 mm to 1.25 m
m) Separate brazing is fixed, and one tip 20 is fixed such that its axial rake angle is smaller than the rake angle of the other tip 21.

Furthermore, the drills shown in Fig. 8 (A) and (B) are so-called miniature drills used for machining the printed circuit board, and in order to reduce the frictional resistance with the workpiece, The end portion is formed to have a smaller diameter than the tip portion.

[Experimental Example] Next, the effects of the present invention will be made clearer by explaining an experimental example.

Diameter of conventional drill used: 20 mm Overall length: 230 + nm Blade length: 120 mm Number of teeth: 2 Helix angle: 30° ( Common to 2 cutting edges) (Axial rake angle) Invention Product The shape and dimensions are different from each other except that the tip of the chip discharge groove on one side has been additionally machined as described above to make the rake angle of one cutting edge 25°. Same as conventional product. The additional machining length (see Figure 2) is 20Illffl.

Cutting conditions: Cutting speed: 23m/min Feed rate:
・・・・・・ 50mm/min hole depth ・・・・・・
109 mm (blind hole) work material ・・・・・・
JIS 90M430 cutting oil ・・・・・・ Water-insoluble cutting oil Processing number ・・・・・・ 40 When drilling was performed under the above conditions,
In the drill of this invention, ribbon-shaped chips as shown in FIG. 5 were continuously generated from both cutting edges. Its width W
was about 8.5 mm.

On the other hand, in the conventional drill, spiral chips as shown in FIG. 9 were generated from both cutting edges. Its diameter is 1
It was about 1 mm. In addition, as a result of improved chip evacuation, when drilling holes with the drill of the present invention, it is possible to suppress the temperature rise of the workpiece after drilling.
In the case of a conventional drill, the temperature of the workpiece is 130 to 14
In contrast, in the case of the drill of this invention, the temperature reached 0°C.
The temperature was 80°C to 85°C.

[Effects of the Invention] As explained above, according to the drill of the present invention, the rake angles in the axial direction of the two cutting edges are set to different angles from each other, so that the chips generated by the conventional drill are The space required is small compared to the chips generated. Therefore, it is possible to prevent chip clogging.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention.
The figure is a partially omitted side view, Figure 2 is an enlarged view of the tip, Figure 3 is a view from the ■ arrow in Figure 2, and Figure 4 is the margin section 16.
．． 17, FIG. 5 is a diagram showing chips generated by the drill of the present invention, FIGS. 6(A) and (B) are diagrams showing other embodiments of the present invention, and FIG. A partially omitted side view thereof, FIG. 6(B) is a view taken in the direction of arrow B in FIG. 6(A), and FIGS. 7(A) and (B) show still another embodiment of the present invention. FIG. 7(A) is a side view thereof, FIG. 7(B) is a view taken from arrow B in FIG. 7(A), and FIGS. 8(A) and (B) are still other embodiments of the present invention. 8(A) is a side view thereof, FIG. 8(B) is a view taken along arrow B in FIG. 8(A), and FIG. 9(A). (B) shows an example of a conventional drill, Fig. 9 (A) is a side view thereof, Fig. 9 (B) is a view taken along arrow B in Fig. 9 (A), and Fig. 10 shows an example of a conventional drill. FIG. 3 is a diagram showing generated chips. 11...Drill body, 12.13...
Cutting blade, 14.15...Chip discharge groove.

Claims (1)

[Claims] 1. A drill comprising two cutting edges formed at the tip of a tool body, characterized in that rake angles in the axial direction of the two cutting edges are set to different angles from each other.