JP2003165010A - Solid gun drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid gun drill with a small diameter capable of securing a cutting oil amount. <P>SOLUTION: The solid gun drill 1 is made integrally of cemented carbide, and an oil hole 14 extending toward a driver 7 is drilled in a land 6 of a tool cutting edge 2. The oil hole 14 has a long hole shape in the view of the tip of the tool with reference to the circumferential direction of a bearing surface 10, and the ratio A/B of cross section A of the oil hole 14 to cross section B of a chip discharge groove is set within the range of 35 to 50%. The ratio W/L of width W of the oil hole to length L of the oil hole is set within the range of 40 to 60%. In the inner wall of the oil hole 14, the curved inner wall 14a is disposed on the bearing surface 10 side and the linear inner wall 14b is disposed on the chip discharge groove 5 side. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid gun drill and, more particularly, to a solid gun drill having a small diameter, for example, a tool diameter of 3.0 mm or less, so that the chip discharging property can be improved.

[0002]

2. Description of the Related Art Conventionally, this type of solid gun drill has been
The tool blade tip portion and the pipe-shaped body are integrally formed of cemented carbide, and a round hole-shaped oil hole is normally opened in the tool blade tip portion. The cross-sectional area of the conventional oil hole is set to be less than about 30% of the cross-sectional area of the chip discharge groove.

[0003]

Therefore, in the above-described solid gun drill, at the time of drilling, the discharge amount of the oil hole becomes small in the vicinity of the chip discharge groove of the tool edge, and as a result, the chip discharge property is reduced. It became worse and it was necessary to increase the discharge pressure of the processing machine.

By the way, in a gun drill having a tool diameter of 3.0 mm or less, in order to improve the chip discharging property, from the viewpoint of securing the discharge amount of the cutting oil as described above, it is 10 MPa.
Cutting hydraulic pressure of more than is required. As a result, there is a problem in that the required pressure cannot be set high depending on the hydraulic specifications of the processing machine.

In view of the above, in order to solve the above-mentioned problems, the present invention can improve the structure of the oil hole to increase the discharge amount of the cutting oil and can be applied to a processing machine having a low hydraulic pressure. It provides a small diameter solid gun drill.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is intended for a small diameter solid gun drill in which a tool cutting edge portion and a pipe-shaped main body are integrally formed of cemented carbide. This is to improve the oil hole that opens to the land having a circular cross section.

That is, the oil hole is formed large so as to have an elongated hole shape with the circumferential direction of the bearing surface as a reference when viewed from the tip of the tool cutting edge, and the cross-sectional area A thereof is chip discharge. The ratio A to the cross-sectional area B of the groove
/ B is set within the range of 35 to 50%. This is to ensure the supply of cutting oil without impairing the tool strength.

Since the oil hole also depends on the shape from the viewpoint of the tool strength, the width W of the oil hole to the length L of the oil hole may be set within the range of 40 to 60%. It is the one. In this case, regarding the set position of the oil hole, it is preferable that a curved inner wall is provided on the bearing surface side and a linear inner wall is provided on the chip discharge groove side.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the solid gun drill of the present invention will be described below with reference to the drawings.

1 and 2, a solid gun drill 1 has a tool blade tip portion 2 and a pipe-shaped main body 3 which are integrally formed of cemented carbide. The tool blade tip portion 2 has a pair of tip cutting edges. The ridges 4a and 4b are formed as a beveled edge shape. In this case, the tool edge portion 2 and the pipe-shaped body 3
Is formed with a chip discharge groove 5 in the axial direction, and a land 6 having a circular cross section remains in the tool edge portion 2. A driver 7 is provided at the rear end portion of the pipe-shaped body 3.

At the outer peripheral portion of the land 6, an outer peripheral edge 8,
A margin 9 and a bearing surface 10 are formed. In this case, the bearing surface 10 on the outer peripheral side of the land 6 has both sides thereof, that is, the margin 9 side and the heel 1 side.
Outer peripheral relief portions 12a and 12b are formed on the first side, respectively.

On the other hand, in FIG. 3, a pad is provided on the heel 11 side.
13 is formed, and as a result, the outer peripheral clearance portion 12b is formed.
Are formed between the bearing surface 10 and the pad 13. This is to improve the guide function by adding the pad 13, although it depends on the processing conditions.

The land 6 is provided with an oil hole 14 in the shape of an elongated hole with reference to the circumferential direction of the bearing surface 10 when viewed from the tip of the tool cutting edge 2, and the tool cutting edge 2 and the pipe-shaped body 3 are formed. Extending towards. The reason why the shape is limited to the long hole shape is because of a space relation, and in particular, in the case of the round hole, there is a limitation due to the diameter, and it is not possible to secure the lower limit value of A / B = 35% described later.

By the way, in the solid gun drill of the present invention, the sectional area A of the oil hole 14 in the tool edge portion 2 needs to be as low as possible in the vicinity of the chip discharge groove 5, Therefore, the ratio A / B to the cross-sectional area B of the chip discharge groove 5 on the same cross section is 35 to 50.
It is set within the range of%.

If the ratio A / B is less than 35%, the amount of cutting oil discharged from the oil hole 14 is small, and as a result, the chip disposability is deteriorated. The amount of cutting oil is sufficient, but it is excluded because of insufficient tool strength.

Further, the oil hole 14 is provided on the bearing surface in order to reduce the hydraulic loss inside the tool edge portion 2.
When the space between the chip 10 and the chip discharge groove 5 is the width direction and the circumferential direction of the bearing surface 10 is the length direction, the ratio W of the width W of the oil hole 14 to the length L of the oil hole 14 is W. / L is 40
It is preferably set within a range of -60%.

If the ratio W / L of the oil holes 14 is less than 40%, it is excluded because it leads to a decrease in the discharge amount of cutting oil. If the ratio W / L exceeds 60%, the wall thickness on the bearing surface 10 side decreases and the strength becomes insufficient, so it was excluded.

Further, although the oil hole 14 may have an elliptical shape and a long hole shape, in view of securing the discharge amount of cutting oil and the tool strength, the inner surface 14a of the bearing surface 10 has an arc shape. Is preferable, and a shape in which the linear inner wall 14b is formed on the chip discharge groove 5 side is preferable.

(Cutting Example 1) Next, for the solid gun drill of the present invention, a drilling test to which the present invention product, the comparative product and the conventional product are applied will be described. The tool specifications and the like are as follows, but the shape of the oil hole 14 was elliptical except for the round hole of Conventional Example 1. The comparative products 1 to 4 are
The case where one of A / B and W / L was satisfied was set. Tool specification: φ2.0mm Solid gun drill Work material: S45C Cutting conditions: V = 53m / min. F = 0.008mm / rev. Machining hole depth = 85mm Machine: Gundrill machine Discharge pressure = 10MPa As a result, this invention product As shown in Table 1, all of Nos. 1 to 4 were good, but all of Conventional products 1 and 2 and Comparative products 1 to 4 were defective.

Comparative products 1 to 4 are A / B or W / L
Although one of them is satisfied and the other is not satisfied, the following matters were confirmed. That is, regarding A / B, if the numerical value is large, the chip disposability is improved, but if it exceeds the upper limit, the strength tends to be insufficient as in Comparative Example 4, and if it is less than the lower limit, the comparison is made. It was confirmed that the chips tended to be clogged as in Example 1.

Regarding W / L, when the upper limit is exceeded, the strength tends to be insufficient as in Comparative Example 2, and when it is less than the lower limit, chip clogging is observed as in Comparative Example 3. There was a tendency.

(Cutting Example 2) Further, the oil hole 14 in the present invention
Regarding the shape of the, the arc-shaped inner wall seen in FIG. 2 and FIG.
A hole-piercing test was conducted on the one having 14a and the linear inner wall 14b. In this case, regarding the tool specifications, tool diameter = φ3.0m
m, A / B = 0.5, W / L = 0.50, 0.60, and the work material, cutting conditions, and machine were set the same as in Cutting Example 1.

As a result, when W / L = 0.50 and 0.60,
In all cases, the chip disposal and the tool strength were sufficient, and they were more effective than the oil hole 14 having the elliptical shape of Cutting Example 1 in terms of wall thickness. The reason for this is that on the upper limit side of A / B, W / L
It is necessary to secure the tool strength due to the influence of
This is because it is particularly required to effectively use the space of the land 6.

FIG. 4 shows a modified example corresponding to FIG. 1, in which the same parts are designated by the same reference numerals, but the difference is that the step portion 15 is formed on the tool blade tip portion 2 and the pipe-shaped main body 3. The back taper is continuous without being formed. This is to increase the tool rigidity by eliminating the step portion 15.

Therefore, the solid gun drill 1 shown in FIG.
If the ratios A / B and W / L of the oil holes 14 described above are applied to the above, a more effective effect can be obtained.

The solid gun drill 1 of the present invention is
In the present embodiment, the beveled cutting edge shape is applied, but it can also be applied to a notch type or stack point type cutting edge shape (not shown) according to changes in cutting conditions, a work material, and the like.

Further, the solid gun drill 1 of the present invention is
Al ₂ O ₃ , TiC, TiN, TiCNO on the tool edge 2
If a hard film (not shown) such as is coated with a single layer or multiple layers, the wear resistance is further improved and the drilling performance can be improved.

[0028]

As described above, according to the present invention, the oil hole 14 extending from the tool edge portion 2 toward the driver 7 is formed in a long hole shape with reference to the circumferential direction of the bearing surface 10. And its cross-sectional area A is larger than that of the conventional product (A /
B) can be applied.

Therefore, according to the present invention, in a solid gun drill having a small diameter, for example, one having a diameter of 3 mm or less, the amount of cutting oil can be increased without lowering the tool strength, so that the chip disposal can be effectively performed and the drilling performance is improved. Further, since the guide function also functions effectively, there is an advantage that the drilling accuracy can be improved.

Further, the ratio W / width W and length L of the oil hole 14 is W /
Since L is specified within a predetermined range, it is possible to select an appropriate oil hole 14 shape from the viewpoint of tool strength as well, so that there is an advantage that cutting oil can be supplied more effectively.

Further, regarding the shape of the oil hole 14, even if the inner wall 14a having an arc shape and the inner wall 14b having a straight shape are provided, an effective space utilization of the land 6 can be achieved, so that the amount of cutting oil can be reduced without impairing the tool strength. This has the advantage that the number of chips can be increased and effective chip disposal and guide functions can be ensured.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a solid gun drill of the present invention.

FIG. 2 is an enlarged end view of the tool tip view of FIG.

FIG. 3 is an enlarged end view of the modification of FIG. 2 as viewed from the front end of the tool.

FIG. 4 is a front view of a solid gun drill showing a modified example of FIG. 1.

[Explanation of symbols]

1 solid gun drill 2 Tool edge 3 Pipe-shaped body 4a, 4b Tip cutting edge 5 Chip discharge groove 6 lands 7 driver 8 outer ridge 9 margin 10 bearing surface 11 heels 12a, 12b Outer peripheral relief 13 pads 14 oil hole 14a Arc-shaped inner wall 14b straight inner wall 15 step

Claims (3)

[Claims] 1. A tool blade tip portion and a pipe-shaped main body are integrally formed of cemented carbide, and the land of the tool blade tip portion having an oval cross section due to the formation of a chip discharge groove has a tool blade tip portion. In a small diameter solid gun drill in which an oil hole extending toward the driver is drilled, the oil hole has a long hole shape based on the circumferential direction of the bearing surface when viewed from the tip end from the tool blade tip side. The solid gun drill is characterized in that its cross-sectional area A is set such that its ratio A / B is within the range of 35 to 50% with respect to the cross-sectional area B of the chip discharge groove. 2. The oil hole, which has the shape of an elongated hole, has a width direction between a bearing surface and a chip discharge groove.
The ratio of the width W of the oil hole to the length L of the oil hole is W / L
Is set in the range of 40 to 60%, the solid gun drill according to claim 1. 3. The oil hole according to claim 1 or 2, wherein a curved inner wall is provided on the bearing surface side, and a linear inner wall is provided on the chip discharge groove side. Solid gun drill.