JPH0627285Y2 - Brazed carbide drill - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention relates to a cemented carbide twist drill for highly efficient drilling of cast iron, aluminum, steel, etc., in particular, the ratio of the working depth to the cutting edge outer diameter is 3 It is suitable for deep hole drilling.

(Prior Art) Conventionally, as a carbide drill of this type, for example, Japanese Patent Publication No. Sho 61
-58244, Japanese Patent Publication No. 61-58245, etc. are disclosed.

What is found in Japanese Patent Publication No. 61-58244 is that the cross-sectional area of the twist groove gradually decreases as it goes to the shank side, and what is seen in Japanese Patent Publication No. 61-58244 is that the twist groove has Although it is reduced as described above, the groove depth is increased accordingly. Therefore, although what is seen in these publications is to increase the screw rigidity of the tool body, in deep hole machining, the chip discharge space is decreased conversely, which causes chip clogging.

(Problems to be solved by the invention) However, in the drills disclosed in these publications, when the ratio of the hole depth to the diameter of the cutting edge exceeds 3 in the case of drilling a steel hole, the chips are clogged due to the chip space and torque is reduced. Will increase. Therefore, it cannot be used in the deep hole machining in which the ratio becomes 5 described above.

Also, it has been adopted from the past to gradually change the helix angle and groove shape, but this has not been a fundamental solution to chip clogging, and in manufacturing it requires a complicated machining program. It was troublesome.

The present invention intends to solve the above problems by improving the twist drill having an oil hole so as to improve the structure of the chip discharge groove so that the above-described deep hole drilling with a ratio of about 5 can be performed. .

(Means for ameliorating the problems) The present invention has been made in view of the above-mentioned points. A tool body made of a cemented carbide is attached to one end of a tool body made of steel in the shape of a rod, and a tool is There is a twist in the axial direction of the body 1
A pair of chip discharge grooves is formed, and at the tip thereof, a land portion that constitutes a tip flank on the chip and a pair of tip cutting edge ridges are formed in relation to the existence of the chip discharge groove. The land portion provides an improved twist drill, each of which has an oil hole.

The core thickness of the drill is set to 25 to 35% of the outer diameter D of the cutting edge, and the groove width ratio in the cross section is set to 0.4 to 0.8: 1.

Further, in the chip discharge groove, at least one of the opening edges on the outer peripheral side is widened at an intermediate portion in the axial direction, thereby increasing the groove width ratio. In this case, this spread is based on the cutting edge corner portion where the tip cutting edge ridge and the margin on the outer peripheral side intersect, and the axial length L relative to the cutting edge outer diameter D from this cutting edge corner portion toward the shank side. It is set by the ratio L / D. And the axial position where the spread begins is L / D = 0.5-2.
It is in the range of 5.

(Function) The brazing type carbide drill of the present invention has a groove width ratio of 0.4 to 0.8: 1 at the tip portion and the width of the chip discharge groove is small. Chips with a small curl radius are ejected.

Further, after the chips are divided, the elastic width of the chips is released due to the widening of the width of the chip discharge groove.

Therefore, the accumulation of resistance due to chip discharge is reduced,
Even in deep hole machining, it is possible to machine with high efficiency without causing chip clogging.

(Example) An example of a brazed carbide drill of the present invention will be described below.

In FIGS. 1 and 2, (1) is a brazing-type cemented carbide drill, and at one end of a tool body (2) made of steel,
A blade (3) made of cemented carbide is brazed, and at the other end,
A shank (4) is formed.

This tool body (2) is provided with chip discharge grooves (5) (5) accompanied by an axial twist in the outer peripheral part, and the chip oil from the shank (4) side is formed in the center part of the shaft. In the vicinity of the blade body (3) where the supply hole (6) is drilled and the blade body (3) is to be brazed, it branches toward the land portions (7) and (7) to open the oil holes (8) and (8). I am letting you.

Then, the blade body (3) is composed of, for example, two cutting blade pieces (3a) (3a) as shown in FIG. 2, and a non-cutting gap ( 9) is formed. Regarding the tip cutting edge ridge (10) (10) in this case, for example, a symmetric edge type seen in Japanese Patent Publication No. 58-22283 or an improved Japanese Patent Publication No. 61-270010. Applicable to both asymmetric blades. further,
As shown in Japanese Patent Publication No. 58-18163, various blade shapes can be applied, such as a symmetrical blade shape with no non-cutting gap.

The cemented carbide drill (1) configured in this way is applied to the range of the cutting edge outer diameter D of φ10 to 40 mm,
The core thickness is in the range of 25 to 35% of the outer diameter D of the cutting edge, and the groove width ratio A / B in the cross section is 0.4 to
It is within the range of 0.8: 1. Further, the twist angle of the chip discharge grooves (5) (5) is usually set to 15 ° to 35 °. In this case, regarding the core thickness, the normal range of application in the cemented carbide drill is taken into consideration from the viewpoint of tool rigidity.

In addition, the groove width ratio A / B is smaller than the normal one, 0.4 to 0.8: 1.
As shown in Fig. 6 and Fig. 7, the cutting was forced from the condition when the chips spread in the chip discharge groove (5) (5) and the condition when the chips were separated, It is set in consideration of chip discharge so that the curl radius of becomes smaller. When deep-hole machining is performed with a cemented carbide drill, in the range of the groove width ratio A / B described above, since the curl radius of chips is small at the beginning of drilling, chip division is promoted and chip discharge is good.

However, when a deep hole is formed, for example, when the ratio of the hole depth to the outer diameter of the cutting edge exceeds 3, in the above-described groove width ratio, chip clogging occurs due to the chip space. It becomes a problem.

Therefore, in the present invention, the groove width ratio is increased from the middle part of the tool body (2) to solve the problem of chip clogging. This is shown in FIGS. 4 and 5 as a constant change from A / B to A '/ B'.

The way to increase the groove width ratio is to set the chip discharge groove (5) (5) in the cross-sectional direction.
At least one of the opening edges on the outer peripheral side of the blade is widened. In FIGS. 4 and 5, the margin in the blade body (3) is
An example in which the opening edge on the (11) side is widened is shown.

FIG. 4 shows that by removing the hatched portions (7a) and (7a) from both the chip discharge grooves (5) and (5) of the tool body (2),
It is explanatory drawing in the case of expanding the groove width from the opening angle A of the groove on the basis of the rotation center O to the opening angle A ′ by the angle θ (= A′−A). The angle θ is usually set within the range of 3 ° to 15 °.

Fig. 5 shows the ball end mill (2
By removing the hatched parts (7a) and (7a) so that the core thickness is not changed by shifting the Y-axis and Z-axis of (0), the groove width of both chip discharge grooves (5) and (5) is changed to the angle θ. It is explanatory drawing at the time of expanding by (= A'-A). Further, the axial position where the groove width ratio spreads is set by the ratio L / D of the axial length to the outer diameter D of the cutting edge starting from the cutting edge corner portion (12). In this case, the cutting edge corner part (12) is
Where 0) and margin (11) intersect, and also
The axial position where the groove width ratio spreads is specifically L / D = 0.5-2.
It is set within the range of 5. FIG. 1 shows the case where L / D = 2.0. As a result, the cemented carbide drill of the present invention narrows the groove width to reduce the curl radius of the chip and promotes the cutting of the chip until the chip is cut, and after cutting, widens the groove width to generate chips. Relieves elastic strain and facilitates chip evacuation.

Therefore, the cemented carbide drill (1) of the present invention has a small cumulative total of chip discharge resistance, and can be efficiently processed even in a deep hole without causing chip clogging.

The reason why L / D = 0.5 to 2.5 was set for the position where the groove width ratio spreads is because of the degree of processing depth. That is, as shown in FIG. 7, L / D = 0.5 is the position where chip separation begins, and the ratio of the machining depth to the outer diameter of the cutting edge is 5 or more, especially because of the chip discharge space. It is intended for things. Further, L / D = 2.5 is intended for the case where the ratio of the working depth to the outer diameter of the cutting edge is about 3. Regarding the amount of widening the groove width,
The amount of change in the groove width ratio (A '/ B'-A / B) is generally about 0.05 to 0.3, although it varies depending on the cutting conditions. Therefore, even if the groove width ratio A / B is in the range of 0.4 to 0.8: 1, the widened groove width ratio A ′ / B ′ may exist in the above-mentioned range or may exceed it.

Further, in the present embodiment, as for the blade body (3) made of cemented carbide, it was mainly described that a plate-shaped cutting blade piece (3a) was applied, but the invention is not limited to this, and, for example, the actual Kosho Sho 32 -13982
The tip portion including the land portions (7) and (7) may be made of cemented carbide as seen in the publication.

Further, in order to increase the chip discharge space, it is also effective to increase the groove depth constantly from the axial position where the groove width ratio is widened. However, this means reduces the mounting rigidity of the tool body (2) and is therefore generally applied to the carbide drill (1) on the large diameter side.

(Effect of the Invention) As described above, the present invention has the following effects because the groove width of the chip discharge grooves (5) and (5) is widened from the middle.

First, it can be applied to deep hole machining in which the ratio of the machining depth to the outer diameter of the cutting edge exceeds 5. As shown in FIG. 8, the machining depth of S50C (H _B 200 to 230) by the product A of the present invention and the comparative product B with the cutting edge outer diameter D = φ20 mm is 80 mm, 10
This is from the cutting test result at 0 mm.

That is, the product A of the present invention was good at both the working depth of 80 mm and 100 mm, while the comparative product B was at the working depth of 70 mm.
From around mm, there is a tendency for chip jamming and the torque increases,
This is because it was impossible to machine to a depth of 100 mm.

The product A of the present invention has a groove width ratio A / B of 0.65: 1 in the cross section from the cutting edge corner portion (12) to less than 40 mm and is 40 mm.
Thus, the groove width ratio A '/ B' is set to 0.70: 1. In contrast, the comparative product has a groove width ratio A / B of 0.65:
It is a constant value of 1. In this case, the cutting edge shape of the blade body (3) was a spiral blade shape as shown in FIGS. 1 and 2 for both the product A of the present invention and the comparative product.

And regarding the cutting conditions, the cutting speed V = 60 m / min,
Feed f = 0.3mm / rev (f = 0.1mm / re for up to 10mm)
v), and the emulsion 6 times liquid was sprayed from the oil holes (8) and (8). The cutting fluid at this time is 10 / mi at 13 atm.
The amount supplied was n.

A similar test was conducted on a comparative product in which the cross-sectional area of the chip discharge grooves (5) (5) was gradually increased.
Similar to the above, there was a tendency for chip jamming from around 85 mm, and the torque increased when machining 90 mm. It is considered that this is because in the present invention, the release of elastic strain is largely given to the separated chips.

Furthermore, it was also confirmed from the cutting test results as shown in FIG. In this case, the product A of the present invention has the above-mentioned tool specifications, and the product C of comparison has the same outer diameter of the cutting edge and the groove width ratio of 0.69, and the core thickness is gradually reduced. .

And, as the cutting conditions, cutting speed V = 70 m / min, f = 0.24 mm / rev (0.1 mm / rev from bite to 10 mm) is set as a condition where chip clogging is likely to occur, and both are processed at a machining depth of 90 mm. Were compared.

As a result, the product A of the present invention caused chip clogging even at a working depth of 90 mm, whereas the comparative product C began to cause chip clogging near the working depth of 84 mm. In addition, as shown in FIG. 9, in the comparative product in the cutting torque, the comparative product C had a somewhat higher torque, and the torque increased slightly at the time of the removal.

Secondly, the width of the chip discharge grooves (5) and (5) can be configured by a simpler means than the conventional one that gradually changes. This is the tool body (2) as seen in Fig. 4.
Method of cutting by indexing at a certain angle, or
This is because it can be easily obtained by a method of shifting and cutting the YZ axis of the ball end mill as seen in FIG.

Thirdly, even if the chip discharge grooves (5) and (5) are expanded, the tool rigidity does not decrease so much, and the chip discharge grooves (5) and (5) can participate in sufficient cutting. This is clear from the cutting test described above,
This is also confirmed from the results of the rigidity test by the cantilever in the product A of the present invention and the comparative product B described above. That is, as a load, 10 kgf was applied near the corners of the cutting edge (12), and the amount of deflection was measured in the weakest direction. It was 110 μm / 10 kgf for the device A of the present invention and 100 μm / 10 kgf for the comparative product.
It was because there was not such a significant difference.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a brazed carbide drill of the present invention, FIG. 2 is an enlarged bottom view thereof, and FIG. 3 is a view taken along the line III-III in FIG. An enlarged cross-sectional view obtained, FIG. 4 is an enlarged cross-sectional view obtained along the line IV-IV in FIG. 1, and FIG. 5 is an enlarged cross-sectional view showing a modified example.
FIG. 6 is an explanatory view showing a situation in which the chips spread in the chip discharge groove, and FIG. 7 is an explanatory view showing a situation in which the chips are divided.
FIG. 9 is an explanatory diagram showing cutting test results for the present invention product A and comparative product B, and FIG. 9 is an explanatory diagram showing cutting test results for the present invention product and comparative product C. (1)… Carbide drill, (2)… Tool body (3)… Blade, (5)… Chip discharge groove (7)… Land part, (8)… Oil hole (10)… Tip cutting edge ridge, (11)… Margin (12)… Cutting edge corner

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliographic references Sho 59-193613 (JP, U) Actual 61-148513 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A rod-shaped steel tool body (2) is provided with a cemented carbide blade body (3) at one end, and the tool body (2) is twisted in the axial direction. A pair of chip discharge grooves
(5) (5) is formed, and the chip discharge groove is formed at its tip.
(5) In response to the existence of (5), land portions (7) (7) and a pair of tip cutting edge ridges (10) (10) that form the tip flank on cutting are formed. In a brazed carbide drill in which oil holes (8) and (8) are opened in the land portions (7) and (7), respectively, the core thickness of the drill is 25 to 35% of the outer diameter D of the cutting edge. , The groove width ratio in the cross section of the tip portion is set within the range of 0.4 to 0.8: 1, and the chip discharge grooves (5) (5) have at least one of the outer peripheral opening edges in the axial direction. The groove width ratio is increased by being equally widened from the middle part, and this widening starts from the cutting edge corner part (12) where the tip cutting edge ridge (10) and the margin (11) on the outer peripheral side intersect. Is set by the ratio L / D of the axial length L to the cutting edge outer diameter D from the cutting edge corner portion (12) toward the shank (4) side, and the axial position at which spreading begins is L / D = 0.5 Brazing type carbide drills, characterized in that in the range of 2.5.