JPH03117508A - Drill - Google Patents

Abstract

PURPOSE:To improve a cutting performance by forming a sub-groove at the shaft center side of a main groove for discharging a tip, making the core thick ness of the main groove part at 0.45 - 0.6 times of the drill diameter, making the core thickness of a sub groove part at 0.04 - 0.11 times and making the groove width ratio of the main groove at 1.6:1 - 2.5:1. CONSTITUTION:A subgroove 8 is formed by positioning at the shaft center side of a main groove 6 for discharging a chip, the web thickness dimension W2 of the part of the main groove 6 is made within the range of 0.45 - 0.6 times of the drill diameter and the web thickness dimension W1 of the subgroove 8 part is made within the range of 0.04 - 0.11 times of D. Also the groove width ratio of the main groove 6 is formed within the range becoming 1.6:1 - 2.5:1. Accordingly, the web thickness of the part where the subgroove 8 is formed becomes smaller, a chisel edge becomes smaller as well, the chamfering property is improved and also the cutting resistance is reduced. Moreover, the discharging property is improved because of the sectional area of the chip discharging groove of the subgroove becoming larger and also the drilling rigidity is increased with a larger groove width ratio.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a drill, and more particularly to a drill for drilling deep holes that basically does not require thinning.

[Conventional technology]

Conventionally, when drilling deep holes with a drill, the drill rigidity and chip evacuation performance have a large effect on the drill life and processing accuracy. Furthermore, in order to increase the efficiency of drilling using a general drill rather than for deep hole drilling, it is natural to increase the rigidity of the drill and improve the chip ejection performance. As a specific means for increasing this rigidity, increasing the core thickness is often adopted. However, when the core thickness is increased, it becomes necessary to perform thinning to ensure machinability at the chisel portion, and a problem arises in that the skill of this thinning affects machining accuracy. Furthermore, simply increasing the core thickness will reduce the size of the chip ejection groove, which may impair chip ejection performance. As a technique for solving such problems, the inventors of the present invention have already invented a drill with a sub-groove, which was disclosed in Japanese Patent Laid-Open No. 63-93509. This drill has a core thickness of 1 minute in the regrinding area along its axis, so that thinning is not required not only during initial production but also when regrinding. Rigidity can be increased by making the front and back surfaces of the blade protrude into the chip ejection groove more than those of the standard cross-section blade shape, and (by providing the minor groove) Drills whose shape is given by a smoothly continuous curved surface between the heel surface and the back surface of the blade),
It is possible to improve the chip fJL output performance compared to previous high-rigidity drills.

[Invention or problem to be solved]

-1- As mentioned above, the drill disclosed in Japanese Unexamined Patent Publication No. 63-93509 not only does not require thinning, but also has relatively high rigidity and good chip ejection performance. However, when used in actual machining, it is possible to obtain extremely good cutting results in drilling at a normal depth (depth within 3D, where the drill diameter is D). When used in machining, there are still problems with insufficient rigidity and chip ejection. By the way, if the core thickness of a drill is increased, for example, in order to increase drill rigidity, the volume of the chip ejection groove will be reduced at the same time, impairing chip ejection performance. Further, for example, if the core thickness of the tip cutting edge is reduced in order to improve its cutting performance, drill rigidity will be sacrificed. In this way, the specifications of each part are complexly interconnected in various functional (performance) relationships, and the various specifications are set in a well-balanced manner.1. It is an extremely difficult technology to construct a comprehensively excellent drill, and even today, research and development is being carried out by numerous engineers according to their respective purposes. The present invention has been devised in view of the technical problems related to drills as described above and to effectively solve the problems. (7
Therefore, an object of the present invention is to provide a drill that has rigidity that can withstand deep hole drilling and chip ejection performance without sacrificing one of its characteristics, which is that thinning is not required.

[Means for Solving the Problems] A drill according to the present invention has the following configuration in order to solve the above-mentioned conventional technical problems and achieve the object. That is, in the cross-sectional shape perpendicular to the axis within the re-grindable range along the axial direction from the tip of the drill, a minor groove is formed located on the axial center side of the main groove for chip ejection, and the core thickness dimension of the main groove is is within the range of 0.45 to 0.6 times the drill diameter, and the core thickness of the minor groove part is 0.45 to 0.06 times the drill diameter.
It is within the range of 0.11 times, and the -F main groove has a groove width ratio of 1.
．． It is formed within a range of 6:1 to 2.5:1. [Function] In the drill according to the present invention, the minor groove is formed from the cutting edge.
By applying the chip after finishing to the heel surface of the minor groove part, it breaks into chips of appropriate size, and the cross-sectional area of the entire chip ejection groove is larger than that of lapel drills and conventional high-rigidity drills. Improves chip evacuation. Furthermore, even in the part without the minor groove, the groove width ratio of the main groove is 1.6;
By setting a large ratio of 1 to 2.5:1, a large chip ejection space is secured and sufficient chip ejection performance is obtained. However, even if the groove width ratio is set sufficiently large, it does not reduce the core thickness, and the upper groove part (J
The core thickness dimension is 0.45 to 0.6 times the drill diameter, which is larger than the core thickness dimension of conventional high-rigidity drills (up to about 0.40 times the drill diameter), and the core thickness dimension is 0.45 to 0.6 times the drill diameter. provides the drill rigidity required for deep hole drilling. As the core thickness of the main groove portion increases, the radial rake angle of the cutting edge becomes negative (inclined), and as the core thickness of the minor groove portion decreases, the radial rake angle of the cutting edge becomes negative. By changing the inclination direction of the radial rake angle of the next cutting edge to the positive side, the cutting edge shape in the cross-sectional shape perpendicular to the axis protrudes toward the main groove side in a roughly triangular shape. On the other hand, as the groove width ratio increases, the heel surface of the land part recedes (in the direction of thinning the wall thickness of the land part), but as the cutting edge side protrudes triangularly as described above, the land part It compensates for the decrease in wall thickness of the part and suppresses the decrease in rigidity. In particular, the roughly triangular protruding portion guides the generated chips along the outer peripheral slope of the triangle, resulting in smooth flow of the chips. By making the core thickness of the minor groove part sufficiently small (0.04 to 0.11 times the drill diameter), the width of the chisel edge is made sufficiently small, which improves the biting ability of the drill into the work material. Do well. Therefore, by preventing the occurrence of the so-called walking phenomenon during cutting, it is possible to effectively prevent the center of rotation of the drill from shifting. Furthermore, by making the chisel edge smaller, cutting resistance can also be reduced. Therefore, there is no need to perform thinning, and the skill of thinning does not affect processing accuracy. Thinning is no longer necessary during re-grinding, and only the cutting edge at the tip of the drill needs to be sharpened.

【Example】

Embodiments of the drill according to the present invention will be described below with reference to FIGS. 1 to 7. FIG. 1 is an axis-perpendicular cross-sectional view of the portion where the minor groove is formed in the cutting edge of a drill according to an embodiment of the present invention, FIG. 2 is a side view of the cutting edge of the drill of this embodiment, and FIG. FIG. 4 is an end view of the cutting edge of the example drill seen from the axial direction, and FIG. 4 is a cross-sectional view taken perpendicular to the axis of a portion in which the chip ejection groove is only the main groove. The profiles indicated by broken lines and two-dot chain lines in Fig. 1 are shown to clarify the difference from the drill of the present invention, and the profiles indicated by broken lines are the standard cross-sectional flute shape of conventional standard drills. , the back side of the blade 3a and the heel side 3
b is a shape in which the wall surface of the chip ejection groove is formed by a smoothly continuous curved surface. In addition, the profile indicated by the two-dot chain line is the cross-sectional shape perpendicular to the axis of a drill with a minor groove published in Japanese Patent Application Laid-Open No. 63-93509, and 2b is the part with the minor groove and the part with only the main groove. The back side of the blade common to
2c is a heel surface of a portion having a minor groove, 2d is a heel surface of a portion having only a main groove, and 2e is a groove wall surface at the innermost part of the main groove. The drill of this embodiment has a tip ejection sub-groove 8 within a predetermined range along the axial direction from the tip thereof, as shown in the cross-sectional shape perpendicular to the axis in FIG. The chip ejection main groove 6 has a groove width ratio of 2.0:1 and is formed approximately as if the heel portion 2f of the above-mentioned conventional drill with a sub-groove was cut off.
The chip ejection groove occupies a large cross-sectional area. As shown in FIG. 3, the groove width ratio is determined by the central angle α of the groove divided at the intersection 10 of the heel surface 7 of the groove and the second outer surface 9 of the land, and the central angle β of the land. is the ratio of (α
/β): Represented by 1. The core thickness dimension at the part having the minor groove 8 (hereinafter referred to as the minor groove core thickness) Wl is 0.07 D with respect to the drill diameter, and the core thickness dimension at the part having only the main groove 6 (hereinafter referred to as the minor groove core thickness) (referred to as main groove core thickness)
W is 0.5D. As understood from FIGS. 3 and 4, the main cutting edge 4 extends from the tip point 12 of the margin 11 so as to be in contact with the core thickness W of the main groove portion, so that its radial rake angle is While it tilts significantly toward the negative side, the minor groove core thickness W
Since the sub-groove 8 is formed deeply until I becomes sufficiently small, the radial rake angle of the secondary cutting edge 13 formed by the sub-groove 8 approaches approximately 0°. As a result, the blade back surfaces 4a and 13a of the main cutting edge 4 and the secondary cutting edge 13 protrude in a roughly triangular shape toward the main groove 6 side than the blade back surface 3a of the standard drill, and the amount of protrusion is greater than that of the conventional drill described above. It protrudes further toward the main groove 6 side than the amount of protrusion in a drill with a sub-groove. Therefore, even when compared with a conventional drill with a minor groove, the decrease in rigidity due to the heel portion 2f being cut off and the increase in rigidity due to the thickening of the cutting edge portion almost cancel each other out, and the minor groove The rigidity of the part having . As for the drill rigidity in the main groove only part, the main groove core thickness W is much thicker than the conventional drill with a minor groove, so the rigidity is sufficiently increased and it is suitable for deep hole drilling. Durable rigidity can be obtained. However, despite the increased main groove core thickness Wt, the cross-sectional area of the main groove 6 itself is larger than that of a conventional drill with a sub-groove due to the groove width ratio. This also improves chip evacuation and eliminates the risk of chip clogging even when drilling deep holes. Figure 5 is an enlarged axial cross-sectional view of the part where the sub-groove is formed. However, as shown in the figure, a sub-groove 8 is formed within a certain range Q along the axial direction from the tip side of the drill.This range is the range in which the cutting edge can be re-grinded.In this re-grindable range a, , a parallel portion 8a having a constant core thickness W is formed in a core thickness portion within a predetermined range !2 along the axial direction from the tip, and further rearward (shank) from the rear end of this parallel portion 8a. A tapered core thickness is formed at a constant angle of inclination within the remaining range 1.
b is formed. This parallel portion 8a provides rigidity to the cutting edge portion, and also contributes to stabilizing the quality of the product by measuring the core thickness dimension of this parallel portion 8a in the quality inspection process at the manufacturing stage of the drill. In other words, if a sub-groove is constructed from only an inclined part without forming a parallel part, when measuring the core thickness of each drill in this sub-groove part using, for example, a micrometer, the position of the measuring tip of the micrometer will be misaligned even a little. The core thickness dimension differs due to the slope ↑1 of the core thickness part (
Therefore, it is necessary to accurately position the probe at the same location in the valley drill, and this is extremely difficult, making it difficult to stabilize the quality of the product in the past. The taper of the inclined portion 8b is 2/100 to 6/100.
is set within the range of j, and this slope 8
Even after re-grinding to point b, the chisel edge that appears on the cutting edge surface is smaller than the chisel edge of a standard drill, and the cutting performance of the drill is excellent. Figure 6 shows the groove width ratio and tool life () for various main groove core thicknesses.
It is a graph diagram showing the relationship with the number of holes drilled. The drill used for the test has an outer diameter (drill diameter D) of 10xi
, main groove length is 95u5, total length is 130 mm, minor groove core thickness is 0.73
jljf, the tip angle is 135°, and the twist angle is 30°. For cutting conditions and 12, the cutting speed is 1411/min, the cutting feed is 0, 08 xi/rev, and the work material is 350C (
118220-240), the cutting length was 60 holes, and emulsion was used for the cutting curve. In the figure, the main groove core thickness is 0.3D where the measurement points are plotted with · and the dashed line shows.
The drill whose measurement points are plotted with X and shown as a solid line is the drill whose main groove core thickness is 0145■), and the measurement points are plotted with ○ and shown with a solid line.1. The main groove core thickness is 0.5D.
Drill, measurement points are plotted with · and shown as a solid line at 11°C.
The drill shown here is a drill with a main groove core thickness of 0.6D, and the measurement points are plotted with .
, 7D drill measurements. Results and) 2) If the main groove core thickness is within the range of 0.45 to 0.6D, the life will be longer.
Outside this range, sufficient tool life cannot be obtained. this is,
Main groove center 19. This is because if it becomes smaller than 0.45D, it will not be possible to secure the drill rigidity required for deep hole drilling.
In addition, if it is larger than 06[), even if the drill rigidity is 1 minute, the radial rake angle of the cutting edge will become too negative, resulting in an excessive increase in cutting resistance, and the main groove for chip ejection will This is because the cross-sectional area is too small (too much), so these negative factors will double the drill rigidity on balance. Figure 7 shows the relationship between main groove core thickness and tool life (number of holes drilled) for various groove width ratios. ) is a graph diagram showing the relationship between The figure shows a drill with a groove width ratio of 1.2:1, and the measurement point is X and the solid line shows a drill with a groove width ratio of 1.
61 drill, the measurement points are plotted with ○ and the solid line shows the drill with a groove width ratio of 2:1, the measurement points are plotted with the blower [・l, and the solid line shows the groove width ratio The measurement results for a drill with a groove width ratio of 24:1, and the measurement points plotted with · and indicated by a dashed line, are for a drill with a groove width ratio of 2.7:l. As a result, in No. 5, the tool life is long when the groove width ratio is within the range of 1.6.1 to 25.1, and a sufficient tool life cannot be obtained outside of this range. This means that in order to obtain the chip ejection properties necessary for deep hole drilling, the cross-sectional area of the main groove must correspond to the groove width ratio of at least 1.6.1. This is because as the value increases, the torsional rigidity of the drill decreases significantly. [Effects of the Invention] As is clear from the above explanation, according to the present invention, the following excellent effects are exhibited. That is, according to the drill according to the present invention, the core thickness of the portion where the minor groove is formed is reduced, and the chisel edge is also reduced.
This improves the bitability of the drill to the work material. Therefore, the occurrence of so-called walking phenomenon during cutting can be prevented, and the rotation center of the drill can be effectively prevented from shifting. Furthermore, by making the chisel edge smaller, cutting resistance can also be reduced. Therefore, there is no need to perform thinning, and the skill of thinning does not affect processing accuracy. Thinning is no longer necessary during re-grinding, and only the cutting edge at the tip of the drill needs to be sharpened. The auxiliary groove increases the cross-sectional area of the chip ejection groove to improve chip ejection performance. In addition, the back surface of the blade of the drill of the present invention, which protrudes further toward the main groove for chip ejection than the back surface of the blade of a conventional drill with a minor groove, has torsional rigidity due to the heel portion being removed by setting a large groove width ratio. By compensating for the decrease in diameter, the core thickness can be increased to about the same level as that of conventional drills with sub-grooves. The back surface of the blade guides the chips along the outer peripheral slope of the triangular shape in the same way as a conventional drill with a minor groove, resulting in smooth flow of the chips.As described above, the drill of the present invention has a conventional minor groove. This makes it possible to obtain chip ejection properties suitable for deep hole machining without sacrificing the machinability advantage of the attached drill, without impairing the drill rigidity required for deep hole machining.

[Brief explanation of drawings]

FIG. 1 is an axially perpendicular cross-sectional view of the portion where the sub-groove is formed in the cutting edge of a drill according to an embodiment of the present invention, FIG. 2 is a side view showing the cutting edge of the drill of this embodiment, and FIG. FIG. 4 is an end view of the cutting edge of the drill according to the present embodiment as seen from the axial direction. FIG. 4 is a cross-sectional view perpendicular to the axis of the portion of the drill according to the present example in which the chip ejection groove is only the main groove. FIG. Fig. 6 is an enlarged axial cross-sectional view of the part where the minor groove is formed; Fig. 6 is a graph showing the relationship between groove width ratio and tool life (number of holes drilled) for various main groove core thicknesses; The figure is a graph showing the relationship between main groove core thickness and tool life (number of holes drilled) for various groove width ratios. 6... Main groove for chip ejection, 8... Minor groove for chip ejection, Q,... Re-grinding possible range, D... Drill diameter, Wl
...Minor groove core thickness, W, ...Main groove core thickness Fig. 1 Fig. 2 Fig. 0 Fig. 3 Fig. 4 Fig. 5 Fig. 6 I-Groove Width Ratio Fig. 7 0.2D 0. 40 0.6D

Claims (1)

[Claims] (1) In the cross-sectional shape perpendicular to the axis within the re-grinding range (l_2) along the axial direction from the tip of the drill, a minor groove (8) is formed located on the axial center side of the main groove for chip ejection (6). The core thickness dimension (W_2) of the main groove (6) is within the range of 0.45 to 0.6 times the drill diameter (D), and the core thickness of the minor groove (8) is within the range of 0.45 to 0.6 times the drill diameter (D). The dimension (W_1) is the drill diameter (D
) is within the range of 0.04 to 0.11 times the main groove (
6) is a drill characterized in that the groove width ratio is formed within a range of 1.6:1 to 2.5:1.