JP2535644Y2 - Drill - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a drill used for drilling a work material made of steel or the like, and more specifically, a depth of at least four times the hole diameter. The present invention relates to a drill capable of performing hole machining with high efficiency.

[Prior art] A drill used for drilling a work material requires various performances depending on the material of the work material, cutting conditions, and the like.
In particular, in drills used for drilling deep holes with a depth of four times or more the hole diameter, whether the chips generated at the tip of the drill can be easily discharged, that is, whether the chip discharge property is good or not is another performance. It is also considered important as a factor that affects the processing efficiency.

Conventionally, as a drill for improving the chip discharge property, for example, as described in Japanese Utility Model Application Laid-Open No. 64-12716, the twist angle of the chip discharge groove is gradually reduced from the middle and the groove width is reduced. Enlarging the rear end side of the chip discharge groove into a linear groove extending parallel to the tool axis, or twisting the front end side of the chip discharge groove as described in JP-A-62-213911. It is known that the rear end side is formed in a linear groove shape while being formed in a groove shape, and the groove width of the linear groove is further enlarged in comparison with the twist groove.

In any of the drills configured as described above, the groove width on the rear end side of the groove is larger than that on the front end side, so that the chip discharging property is improved, and the portion having a large groove width has a linear groove shape. Therefore, the reduction in the torsional rigidity of the tool can be suppressed slightly compared to the case where the groove width is increased while maintaining the shape of the torsional groove.

In addition to the above-described drill, for example, as shown in FIG.
There is also known a configuration in which two curved surfaces 4 and 5 having a small radius of curvature are provided over the entire length of the chip discharge groove 1 so as to enhance the chip dividing effect.

[Problems to be Solved by the Invention] However, among the above-mentioned conventional drills, the two types of drills with the enlarged groove width described above only reduce the chip discharge resistance at the rear end side of the chip discharge groove. No consideration has been given to resistance to chip curl and the promotion of curl near the cutting edge.Therefore, there is a certain limit to the effect of improving chip discharge, and chip discharge at the time of deep hole drilling is still limited. Could not be improved sufficiently. By the way, when drilling a steel material with the above-mentioned drill, the chip depth is good in the range of 2D to 3D with respect to the tool diameter D. The chip resistance suddenly increased, and the thrust load and rotational torque increased. Particularly, in the region exceeding 4D to 5D, the degree of the increase was remarkable, and the machine stopped or even the drill was damaged.

On the other hand, in the drill shown in FIG. 8 described above, although the chips are finely divided and the chip dischargeability itself is improved, the chips are not curled along the groove wall 3 of the chip discharge groove 1,
Rather, since the chips are bent discontinuously at the convex portions between the curved surfaces 4 and 5, and are forcibly cut, the chip discharge resistance at the tip end side of the chip discharge groove 1 is significantly increased, and chatter vibration grows excessively. There is a risk. Therefore, apart from tools made of high-speed steel or the like, hard and brittle carbide drills have been difficult to put into practical use.

This idea was made in such a background,
An object of the present invention is to provide a drill capable of improving the chip dischargeability and being used without problem for deep hole drilling of four times or more the tool diameter.

[Means for Solving the Problems] In order to solve the above problems, the present invention proposes a method in which the tip of the heel side wall surface of the chip discharge groove is spaced apart from the tool rotation center by 0.3D to 045D with respect to the tool diameter D from the tool rotation center. Forming a convex portion having a top at the set position, and forming a surface from the top of the convex portion to a surface connected to the wall surface of the chip discharge groove with a concave curved surface curved with a larger curvature than the heel side wall surface, The projection is formed from the tip of the cutting blade to the middle of the chip discharge groove in the rear end direction, and the groove width of the chip discharge groove is set to be constant from the front end to the rear end.

In this case, the rear end position of the convex portion may be appropriately determined according to the tool diameter, but is preferably set at a position separated from the front end of the cutting blade by 0.5D to 2D toward the rear end side in the tool axis direction.
Also, the core thickness of the tool body is 0.25D to 0.35D, and the groove width ratio is 0.6
It is preferable to set the value in the range of -1.2: 1.

Furthermore, by gradually decreasing the amount of protrusion of the heel side wall surface at least on the rear end side of the convex portion toward the rear end side in the tool axis direction, the rear end of the convex portion is smoothly connected to the heel side wall surface. This can further reduce the chip discharge resistance of the chip discharge groove.

[Operation] According to the above configuration, the chips generated by the cutting blade curl along the concave curved surface of the convex portion having a larger curvature than the heel side wall surface, so that the heel side is provided in the chip discharge groove behind the convex portion. Chips rounded smaller than the wall surface are discharged and smoothly guided to the rear end side of the chip discharge groove.

In this case, by setting the top of the convex part in the range of 0.3D to 0.45D from the tool rotation center toward the heel side,
Since the concave curved surface can be given a sufficient length while maintaining the curvature of the concave curved surface within an appropriate range, the chips can be reliably restrained and smoothly curled, so that the chip discharging resistance at the tip of the chip discharging groove can be reduced. It can be suppressed to a small range.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

As shown in FIG. 1 and FIG.
In the outer periphery of a substantially cylindrical tool body 11, two chip discharge grooves 12, 12 twisted around a tool axis O are formed, and the tip of a wall 13 of the chip discharge groove 12 is Cutting tip 14 made of brass is joined by brazing, and cutting edges 15 and 14 are formed on the ridge line between the rake faces 14a and 14a and the flank faces 14b and 14b of the cutting tip 14.
15 are formed and schematically configured.

As shown in FIGS. 3 and 4, the wall surface 13 of the chip discharge groove 12 has a marginal side wall surface 16 extending substantially straight in the tool radial direction in a cross section perpendicular to the tool axis, and an arc shape in the tool rotation direction in the cross section. And a heel side wall surface 17 which is depressed in the chip discharge groove.
It is constituted by a rake face 14a of a cutting blade tip 14 which is brazed to 12.

On the other hand, as shown in FIGS. 1 to 3, at the tip of the heel side wall surface 17, there are formed projections 18 projecting from the heel side wall surface 17 toward the margin side wall surface 16. I have. These projections 18 have tops 20 at positions slightly receded from the heel 19 of the tool main body 11 toward the tool inner periphery, and the portion extending from the top 20 to the inner periphery is the heel side wall surface 17. It is constituted by a concave curved surface 21 that curves with a larger curvature. These concave curved surfaces 21 have a length substantially equivalent to a semicircular arc, and the inner peripheral ends thereof are smoothly connected to the inner peripheral side of the heel side wall surface 17.

Further, the amount of protrusion of the convex portion 18 from the heel side wall surface 17 on the rear end side is gradually reduced toward the rear end side in the axial direction of the tool body 11, whereby the rear end of the convex portion 18 is And smoothly connected. Further, a portion extending from the top 20 to the outer peripheral side of the convex portion 18 is constituted by an inclined surface 22 that is linearly inclined toward the heel 19, and thereby, the groove width ratio of the tool body 11, that is, the outer peripheral surface of the cutting blade 15, Angle θ ₁ from the end to the heel 19 via the chip discharge groove 12
And the heel 19 from the outer peripheral end of the cutting blade 15 through the outer peripheral surface 23 of the tool.
The ratio θ ₁ : θ ₂ to the angle θ ₂ up to the point is the chip discharge groove 12.
It is constant not only at the portion on the rear side than the portion where the convex portion 18 is provided, but also up to the tool tip side where the convex portion 18 is provided. In short, the groove width ratio θ ₁ : θ ₂ is constant over the entire length of the chip discharge groove 12. FIG. 3 shows an example in which the ridge between the heel side wall surface 17 and the tool outer peripheral surface 23 is not chamfered. However, as shown in FIG. When the chamfer C is applied to the ridge line portion, the same chamfer C may be applied to the outer peripheral end of the inclined surface 22 as a matter of course.

Here, the distance A from the top portion 20 of the convex portion 18 to the tool rotation center P ₀ is determined appropriately according to such material and cutting conditions of the workpiece, 0.3D～0.45D the tool diameter D Is preferably used. The reason is as follows.

That is, when the distance A is less than 0.3D, the concave curved surface
If the curvature (1 / R ₁ ) of 21 is reduced, the circumferential length of the concave surface 21 is insufficient and the chips cannot be curled sufficiently, so the curvature of the concave surface 21 must be set to an excessively large value. However, as a result, there is a possibility that the resistance when the chips are curled greatly increases. On the other hand, in the range where the distance A exceeds 0.45D, the degree of freedom of the curvature and the circumferential length of the concave curved surface 21 that can be set increases, but the chip separation from the convex portion 18 deteriorates and the chip discharge groove 12 The shortage of the groove cross-sectional area at the tip may cause the chip discharge resistance to worsen. It is sufficient that the length of the concave curved surface 21 is as long as approximately a semicircular arc.

Also, the protrusion amount B of the top portion 20 from the heel side wall surface 17 is shown.
Is preferably set in the range of 0.07D to 0.15D with respect to the tool diameter D. If the protrusion amount B is less than 0.07D, the curl curvature of the chips may be too small to sufficiently reduce the resistance between the chip after curling and the chip discharge groove 12, while the protrusion amount B may be 0.15D. This is because, if it exceeds, the curl curvature of the chips becomes too large, and the chip discharge resistance may be rather increased.

Further, it is preferable that the distance 1 from the outer peripheral end of the cutting blade 15 to the rear end of the convex portion 18 is set in the range of 0.5D to 2D with respect to the tool diameter D. If the distance l is less than 0.5D, the effect of accelerating the curl of the chips by the projections 18 may not be sufficiently exhibited,
On the other hand, if the distance l exceeds 2D, the dischargeability of the chips after curling is deteriorated and the cutting resistance may be increased.

The groove width ratio θ ₁ : θ ₂ is preferably in the range of 0.6 to 1.2: 1. Chip discharge groove 1 if the groove width ratio is less than 0.6: 1
This is because the chip discharge resistance may be deteriorated due to an insufficient cross-sectional area of 2, and if it exceeds 1.2: 1, the torsional rigidity of the tool may be deteriorated and the machining accuracy may be impaired. For the same reason, the core thickness d of the tool body 11 is 0.25D with respect to the tool diameter D.
It is preferably in the range of 0.35D.

In the drawing, reference numeral 24 denotes a shank for gripping the drill 20, and 25 denotes a guide hole for guiding the cutting oil supplied from the end face of the shank 24 to the tool tip, and an oil hole 26 opening at the tool tip.
The cutting oil can be supplied to the cutting blade 15 by being communicated with the cutting blade 15.

However, in the drill 10 configured as described above, since the convex portion 18 having the concave curved surface 21 is formed at the tip of the chip discharge groove 12, the chip growing along the rake surface 14a is not formed. The curl is promoted by being reliably restrained by the concave curved surface 21.
Moreover, by setting the apex 20 of the convex portion 18 within a certain range from the tool rotation center P _{0, the} curvature and length of the concave curved surface 21 are limited to a range in which the chips are smoothly and reliably curled. Therefore, there is no effect that the chip is bent discontinuously. Therefore, the resistance when the chip is curled is small, and the chip discharge resistance on the tip end side of the chip discharge groove 12 is suppressed.

In addition, the curl curvature of the chips is larger than the curvature of the heel side wall surface 17 due to the curl along the concave curved surface 21.Therefore, the rounded chips smaller than the heel side wall surface 17 are discharged behind the convex portion 18. Will be done. Therefore, the projection 18
The chip discharge resistance from the rear end to the rear end of the chip discharge groove 12 is also reduced. In this case, in particular, since the chip discharge groove 12 is twisted at a constant torsion angle over the entire length, a force that pushes the chip toward the rear end of the tool due to the rotation of the drill acts over the entire groove length. Discharge is facilitated.

Also, the portion of the convex portion 18 on the outer peripheral side from the top 20 is a sloped surface.
22, the concave surface 21 on the outer peripheral side of the top 20
The separation of the chips curled along with the convex portion 18 is promoted, and the chip discharge resistance at the tip end side of the chip discharge groove 12 is also reduced. Incidentally, if the concave surface 21 is simply extended to the outer periphery of the tool without providing the top 20, the chip separation from the concave surface 21 becomes poor, and the groove cross-sectional area is significantly reduced, so that the chip discharge resistance may deteriorate. There is.

Further, in the present embodiment, the groove width ratio on the rear side of the chip discharge groove 12 is not required to be increased due to the effect of reducing the chip discharge resistance by the convex portion 18, and the groove width ratio is set to a range that does not impair the torsional rigidity of the tool. , So that the machining accuracy is prevented from deteriorating due to a decrease in tool rigidity.

In addition, in this embodiment, since the rear end of the convex portion 18 smoothly continues to the heel side wall surface 17, the chip curled by the convex portion 18 is smoothly discharged to the rear side, and the chip discharge resistance is reduced. It is further reduced. However, even if the rear end of the convex portion 18 is discontinuous with respect to the heel side wall surface 17, it is possible to obtain a constant chip discharge resistance reducing effect.

In this embodiment, in particular, the portion on the outer peripheral side of the top portion 20 of the convex portion 18 is formed by the inclined surface 22 reaching the heel 19, but the present invention is not limited to this. For example, the sixth
As shown in the figure, it may be constituted by a concave curved surface 30 reaching from the top 20 to the heel side wall surface 17, and the surface shape is also the top
As long as it does not protrude beyond 20, it is not limited to a concave curved surface or an inclined surface, but can be variously deformed such as an arc surface. Further, it is not necessary to form the apex portion 20 of the convex portion 18 at an acute angle end, and the cross-sectional shape such as a spherical shape can be appropriately changed.

In the present embodiment, the tip of the convex portion 18 is continuous with the tool tip surface. However, the present invention is not limited to this.
Even if the tip of the tool 18 is retracted from the tool tip surface, there is no problem as long as the chip 18 is located at a position where the chips generated by the cutting blade 15 can be restrained.

Further, in this embodiment, a drill in which the cutting edge tip 14 is brazed and joined is described in particular, but it is a matter of course that other solid drills and throw-away drills can be similarly applied.

Next, the result of a cutting test in which the quality of chip discharge during drilling was confirmed using the drill of the above embodiment will be described with reference to FIG. As a comparative example, the results of a cutting test performed on a conventional drill in which the twist angle of the chip discharge groove is gradually reduced to form a straight groove on the rear end side of the groove and the groove width ratio is also increased. The cutting conditions are as shown below, and the dimensions of each part of the drill are as shown in Table 1. Further, as a scale for judging whether the chip discharge property is good or not, since the cutting resistance increases as the chip discharge property deteriorates, the required cutting power at the time of cutting is measured and compared.

- tool diameter D ...... 20 mm, machining depth ...... 140 mm (7D) through hole, used machinery ...... vertical machining center, the work material ...... SCM440 (hardness: H _B 220), cutting oil ...... aqueous emulsion ( Supply pressure 5kg / cm ² ) ・ Cutting speed …… V = 70m / min. ・ Feed speed …… f = 0.3mm / rev. As is apparent from FIG. 7, the drill according to the present invention does not deteriorate the chip discharge performance even when the hole depth is increased, so that the cutting power hardly increases even in the region where the processing depth exceeds 4D, and 5.8 kw. Is stable in the range slightly below. In contrast, in the comparative example, the cutting power increased remarkably in the region where the hole depth exceeded 4D, and a maximum of 9.0 kW of cutting power was required near the hole exit, that is, just before the penetration of the work material. There is a significant difference.

[Effects of the Invention] As described above, according to the present invention, the chips are curled small along the concave curved surface of the convex portion, so that the chips can be discharged without increasing the width of the rear end side of the chip discharge grooves. Chip discharge resistance on the rear side of the convex part of the groove is significantly reduced, and
Since the position of the top of the projection is limited to a certain range, the chips are reliably and smoothly curled at the tip of the chip discharge groove, and the chip discharge resistance at the tip of the chip discharge groove is suppressed to a small range. There is an excellent effect that even when drilling a hole having a depth of more than 4 times, it is possible to perform the drill without any problem by eliminating the risk of stopping the machine or breaking the drill. Further, by keeping the groove width ratio constant, tool rigidity can be ensured, and deterioration of machining accuracy can be prevented.

[Brief description of the drawings]

1 to 4 show one embodiment of the present invention.
1 is a side view of the drill, FIG. 2 is a view taken in the direction of the arrow II in FIG. 1, FIG. 3 is a sectional view taken along the line III-III in FIG. 1, and FIG. FIG. 5 is a cross-sectional view showing a modification of the above embodiment, FIG. 6 is a cross-sectional view showing another modification, and FIG. 7 is a cutting test result of the present invention and a comparative example. FIG. 8 is a sectional view showing a conventional example. 10 Drill, 11 Tool body, 12 Chip discharge groove, 13
…… the wall surface of the chip discharge groove, 14 …… Cutting tip, 14a …… Rake surface, 15 …… Cutting blade, 17 …… Heel side wall surface, 18 …… Protrusion, 19 …… Heel, 20 …… Top , 21 …… Concave surface, P ₀ …
... Tool rotation center.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Matsuda 1528 Nakashinda, Yokoi, Kobe-cho, Anpachi-gun, Gifu Pref. )

Claims (4)

(57) [Scope of request for utility model registration] 1. A chip discharge groove extending from the front end of the tool main body toward the rear end side is formed in an outer peripheral portion of the tool main body, and a cutting edge is formed at a ridge line between the front end of the wall surface of the chip discharge groove and the front end surface of the tool. In the drill provided with a, at the tip of the heel side wall surface of the chip discharge groove, a convex portion having a top at a position 0.3D to 0.45D away from the tool diameter D from the tool rotation center to the heel side And a surface from the top of the projection to the wall surface of the chip discharge groove is formed as a concave curved surface that is curved with a larger curvature than the heel side wall surface, and the projection is formed of the cutting blade. A drill formed from a front end to a halfway in a rear end direction of the chip discharge groove, and a groove width of the chip discharge groove is set to be constant from a front end to a rear end. 2. The drill according to claim 1, wherein a rear end position of the projection is shifted from a front end of the cutting blade to a rear end side in a tool axis direction.
A drill characterized in that it is set at a position separated by 0.5D to 2D, the core thickness of the tool body is set to 0.25D to 0.35D, and the groove width ratio is set to a range of 0.6 to 1.2: 1. 3. A projecting amount of at least a rear end of the convex portion from the heel side wall surface is gradually reduced toward a rear end side in a tool axial direction, so that a rear end of the convex portion is in contact with the heel side wall surface. The drill according to claim 1 or 2, wherein the drill is smoothly continuous. 4. A tip end of a wall surface of the chip discharge groove is formed by a rake face of a cutting edge chip brazed to the chip discharge groove, and a ridge line between a rake face and a flank face of the cutting edge chip. The drill according to any one of claims 1 to 3, wherein the cutting edge is formed.