JPH0688168B2 - Drilling tool - Google Patents

Description

TECHNICAL FIELD The present invention relates to a drilling tool in which a twisted chip discharging groove is provided on a front end side and a linear chip discharging groove is provided on a rear end side. is there.

"Prior Art" Conventionally, as this type of drilling tool, for example, a drill 1 as shown in Figs. 8 to 11 has been known.

This drill has two cutting edges 12,12 on the tip of the tool body 11.
Is provided. Further, on the outer periphery of the tool main body 11, two twisted chip discharge grooves 13, 13 are provided from the cutting blades 12, 12 toward the rear end side, and further, these twisted chip discharge grooves 13, 13 are formed. From the rear end toward the rear end side of the tool body 11, linear chip discharge grooves 14, 14 provided in parallel with the axis of the tool body 11 are provided. Then, as shown in FIG. 9, the core thickness between the two twisted chip discharge grooves 13 and 13 and between the two linear chip discharge grooves 14 and 14 varies from the tip to the rear end of the tool body 11. As shown in FIGS. 10 and 11, the twisted chip discharge groove 13 and the straight chip discharge groove 14 have an equal groove width ratio R = 2θ. It is formed at / 360 °.

"Problems to be Solved by the Invention" By the way, in the drill 1 described above, the core thickness is formed to increase from the front end toward the rear end, and the groove of the twisted chip discharge groove 13 is formed. Width ratio and linear chip evacuation groove
The groove width ratio of 14 is formed to be equal. As a result, a straight chip discharge groove is provided for the groove cross-sectional area of the twisted chip discharge groove 13.
The groove cross-sectional area of 14 becomes smaller. For this reason, there is a problem that the chip discharge property in the linear chip discharge groove 14 is deteriorated.

In particular, when a work is rotated by a lathe or the like to fix the drill to make a hole, it is not possible to expect discharge of chips due to centrifugal force because the drill is not rotating. Also,
If the position of the straight chip discharge groove 14 is fixed as shown in FIG. 12, for example, the chip discharge property of the chip discharge groove 14 located on the upper side is deteriorated. For this reason, the chip discharging property from the linear chip discharging groove 14 is further deteriorated.

On the other hand, by making the core thickness constant from the front end side to the rear end side, the groove cross-sectional area of the linear chip discharge groove 14 is made equal to the groove cross-sectional area of the twisted chip discharge groove 13, and the chip discharge property is improved. It is also possible to do it. However, in this case, the rigidity of the drill is lowered and chatter, vibration and the like occur, which is not preferable.

"Object of the Invention" An object of the present invention is to provide a drilling tool capable of improving the chip discharging property without reducing the rigidity of the drilling tool.

[Structure of the Invention] The present invention has a structure in which the groove width ratio of the linear chip discharge groove is set to be larger than the groove width ratio of the twisted chip discharge groove.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 is a view showing a drill (drilling tool) 2 according to the present invention. The drill 2 has a tool body 21. Two tips 22 and 22 are provided at the tip of the tool body 21, and the cutting edges 22a and 22a are provided to the tips 22 and 22, respectively. Further, the cutting edge is provided on the outer periphery of the tool body 21.
22a, 22a or two twisted chip discharge grooves 23, 23 towards the rear end
Is provided. The twisted chip discharge groove 23 is formed in an arcuate cross section, and its groove width ratio is constant from the front end side to the rear end side. Also, the tool body 21
On the outer periphery of the linear chip discharge grooves 24, 2 from the rear end of the twisted chip discharge grooves 23, 23 toward the rear end of the tool body 21.
4 are provided. The linear chip discharge groove 24 is provided in an arcuate cross section in parallel with the axis of the tool body 21, and the groove width ratio is constant from the front end side to the rear end side. As shown in FIG. 2, the core thickness between the two twisted chip discharge grooves 23, 23 and between the two linear chip discharge grooves 24, 24 varies from the tip to the rear end of the tool body 21. It is formed so that it gradually becomes thicker.

In such a drill, the linear chip discharge groove 24
Are formed so that the groove width ratio thereof is larger than that of the twisted chip discharge groove 23. That is, as shown in FIGS. 3 and 4, the groove width ratio of the twisted chip discharge groove 23 and the groove width ratio of the linear chip discharge groove 24 are respectively X = 2α / 3.
If 60 ° and Y = 2β / 360 °, X <Y is set. In addition, as a method of widening the groove width of the linear chip discharge groove, there are a method of expanding both sides of the groove and a method of expanding one side of the groove. That is, as shown in FIGS. 5 (A) and 5 (B), a method of expanding the portions X and Y on both sides of a conventional groove (shown by a chain double-dashed line), and FIGS. As shown in B), a method of expanding the part X on one side thereof, and
As shown in FIGS. (A) and (B), there is a method of expanding the portion Y on one side, and either method may be adopted.

In this way, in this drill 2, the groove width ratio of the linear chip discharge groove 24 on the rear end side is made larger than that of the twisted chip discharge groove 23 on the tip end side while maintaining the core thickness taper. The groove cross-sectional area of the straight chip discharge groove 24 can be larger than or equal to the groove cross-sectional area of the twisted chip discharge groove 23. Therefore, it is possible to improve the chip discharge property while preventing chattering, vibration and the like due to the reduction in drill rigidity. Also, when drilling by fixing the drill with a lathe etc., the groove width is wide,
The chip discharging property can be improved.

In the above embodiment, the groove width ratio of the twisted chip discharge groove 23 is constant from the front end side to the rear end side, and the groove width ratio of the linear chip width groove 24 is also the front end side. It is made constant from the rear end side. However, the present invention is not limited to this, and the groove width ratio may be gradually increased from the tip of the twisted chip discharging groove to the rear end of the linear chip discharging groove.

Further, in the above-mentioned embodiment, the chip discharge groove is formed in an arc shape in cross section, but it is not limited to this and may be formed in any shape such as a U-shape in cross section.

[Advantages of the Invention] As described above, according to the present invention, since the groove width ratio of the straight chip discharge groove is made larger than the groove width ratio of the twisted chip discharge groove, the rigidity of the drill is maintained. , The effect of being able to improve the chip discharge performance while preventing chattering and vibration, and particularly the effect of exhibiting good chip discharge performance even when the drilling tool is fixed and used. .

[Brief description of drawings]

1 to 7 are views showing an embodiment of the present invention, in which FIG. 1 is a side view thereof, FIG. 2 is a sectional view taken along its length direction, and FIG. 2 is a sectional view taken along the line III-III in FIG. 2, FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1 and FIG. 2, and FIG. Fig. 5 (A) is a cross-sectional view thereof, Fig. 5 (B) is a view in the direction of arrow K in Fig. 5 (A), and Fig. 6 is a state in which one side of the groove is widened. FIG. 6 is a diagram showing FIG.
6A is a sectional view thereof, FIG. 6B is a view taken in the direction of arrow L in FIG. 6A, and FIG. 7 is also a view showing a state where one side of the groove is widened. ) Is a sectional view thereof, FIG. 7 (B) is a view in the direction of arrow M in FIG. 7 (A), and FIGS. 8 to 12 are views showing a conventional drill. Its side view, FIG. 9 is a sectional view taken along its length, and FIG.
11 and 12 are sectional views taken along line XI-XI in FIGS. 8 and 9, and FIG. 12 is a sectional view taken along line XI-XI in FIG. 8 and FIG.
The figure is a cross-sectional view showing the angle of the chip discharge groove when the drill is fixed. 2 …… Drill (drilling tool), 21 …… Tool body, 23 ……
Twisted chip discharge groove, 24 ... Straight chip discharge groove.

Claims (1)

[Claims] 1. A chip discharge groove twisted from the tip of the tool body toward the rear end side is provided, and the chip discharge groove is twisted from the rear end toward the rear end side of the tool body and is parallel to the axis of the tool body. In a drilling tool provided with a linear chip discharge groove provided in, the groove width ratio of the linear chip discharge groove is made larger than the groove width ratio of the twisted chip discharge groove. .