JPS60177809A - Drill - Google Patents

Abstract

PURPOSE:To improve the strength of drill as much as possible by setting the diameter of web thickness section in the range of 25-35% of drill diameter while the groove width ratio in the range of 0.4:1-0.8:1 thereby suppressing increase of cutting resistance and deterioration of chip discharge function. CONSTITUTION:In the cutter end face direct-view profile, the radial rake angle of cutter positioned at least 2/3 of drill diameter to the outercircumference is set to -5 deg.- positive angle. The strength of drill is improved through increase of web thickness ratio and decrease of groove width ratio. Increase of cutting resistance is suppressed through increase of radial rake angle theta2 of cutter while deterioration of chip discharge function is suppressed through decrease of relative distance.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a high-speed steel drill, and in particular, to a drill made of high-speed steel, and in particular, to a drill made of high-speed steel, which is capable of increasing the strength as much as possible while suppressing an increase in cutting resistance and a decrease in chip evacuation function. This is about a drill that can be done.

[Technical background of the invention and its problems] High-speed steel drills have traditionally been used for double-drilling operations in general steel materials, cast iron, and the like. Originally, a drill advances while discharging chips generated by drilling to the outside of the hole through its own groove. In order for this drilling work to be performed efficiently, it is required that the cutting resistance be small and that the chips be discharged smoothly, and the quality of the chip discharge also affects the increase or decrease of the cutting resistance. .

In particular, the increase in cutting resistance becomes more significant as the drilling depth increases.

Further, the drill is required to have sufficient strength to withstand the cutting forces acting on it. However, if the area of the groove is increased in order to improve the chip evacuation function, the area of the thick core portion will become smaller, which inevitably reduces the cutting resistance, especially the thrust, but on the other hand, this creates the dilemma of insufficient strength. We must maintain a good balance between these relationships.

Further, the strength of a drill is given not only by the toughness and elasticity of the material itself, but also by the rigidity (bending rigidity and torsional rigidity) that depends on the shape.

Therefore, the shape that governs the strength of a conventional drill will be explained with reference to FIG. 1, which shows the shape of the cutting edge when viewed directly from the end surface.

The part 1 shown by the broken line in the figure is the core thickness part,
This is a solid portion in which the groove portion 2 is not formed. As is well known, the drill has a thick core portion 1, a groove portion 2 serving as a discharge passage for chips, and a cavity portion 2 serving as a thick wall portion, which are formed in a spiral manner around the thick core portion 1. Therefore, the ratio of the diameter C of the core thick part 1 to the drill diameter (hereinafter referred to as the core thickness ratio and expressed as a percentage) is related to the strength of the drill, and the circumference of the groove part 2 to the circumference A of the cavity part 3. The ratio of length B (hereinafter referred to as groove width ratio and expressed as B:A) similarly affects the strength of the drill. These two factors can be considered to be the factors that mainly control the strength of the drill in terms of its shape. In other words, the drill strength increases as the core thickness ratio increases and the groove width ratio decreases.

Fig. 2 is a graph showing this relationship in terms of torsional rigidity ratio at each value of core thickness ratio and groove width ratio. and its value is shown in what proportion. In the figure, samples (a) to (d) are the shapes of general conventional drills, and the groove width ratio of each sample is (a).
and (c) are 1+1. The ratio of (b) and (d) is 1.3:1. In addition, samples (BO) to (CH) are examples in which the core thickness ratio is large and the groove width ratio is small, and the groove width ratio of each sample (E) and (C) is 0.4:1. (g) and (ch) are 0.
8:1T: Yes. As shown in the figure, it is clear that samples (H) to (H) exhibit good torsional rigidity ratios and are excellent in terms of strength.

However, simply increasing the core thickness ratio and decreasing the groove width ratio will result in an increase in cutting resistance and a decrease in the chip discharger 11, and the range in which these values can be taken will inevitably be limited. Conventional general values were a core thickness ratio of 15% to 23% and a groove width ratio of 1:1 to 1.3+1.

In addition, regarding the web taber, the well-known appropriate gradient and (
is being pulled.

FIG. 3 shows the shape of a conventional product called a thick-core drill, as viewed directly from the incisal end surface, which was devised to eliminate the general restrictions on upper) E-throttle. In this example, the core thickness ratio is set to be approximately 50%. In other words, the core thickness ratio is set large to increase strength, but simply increasing the core thickness ratio will result in a smaller groove area, so a chip pocket 4 is provided at the tip of the drill. Furthermore, the heel portion 5 is rounded to prevent concentration of shear stress and increase torsional rigidity. However, in this case, although the area of the chip pocket 4 is large, the chip pocket has a cross section different from that of the discharged chips, so it cannot be said to be an effective groove shape, but rather a rounded part of the heel part 5. This can cause the drill to break due to chipping.
<There was a risk. Therefore, the conditions under which this type of drill can be used are limited to a narrow range due to the shape of the chips.

OBJECT OF THE INVENTION] In view of the above-mentioned circumstances, the present invention was devised to effectively improve the performance of a drill.

Therefore, an object of the present invention is to provide a drill that can increase the strength as much as possible while suppressing an increase in cutting resistance and a decrease in chip evacuation function.

[Summary of the Invention] The present invention is characterized in that the diameter of the core thick portion is 25% to 35% of the drill diameter.
and the groove width ratio is set within the range of 0.4:1 to 0.8:1, and the rake angle in the radial direction of the cutting edge located at least 2/3 of the drill diameter on the outer peripheral side is set as follows. -5°
The above object is achieved by setting the cutting edge within a positive range and also by bringing the relative positional relationship between the cutting edge and the groove walls facing each other close to each other.

[Embodiments of the Invention] A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

Fig. 4 is a side view showing the shape of the cutting edge of the drill according to the present invention when viewed directly from the end surface, and Fig. 5 shows the schematic configuration of the tip portion thereof.
FIG.

In the figure, the diameter C of the core thick portion 1 (indicated by a broken line) is set within a range of 25% to 35% of the drill diameter. Further, the ratio of the circumferential length of the groove portion 2 which is the space portion to the circumferential length A of the ridge portion 3 which is the thick wall portion is set within the range of 0°4:1 to 0.8:1.

However, compared to conventional drills, the core thickness ratio is larger and the groove width is wider.
The ratio has been reduced.

Next, the cutting edge 6 located on the outer peripheral side of at least 2/3 of the drill diameter has a rake angle θ of 15° in the radial direction.
~ positive range, and the cutting edge shape forms a concave arc.

Also, a point P with respect to an imaginary reference line connecting a point P1 at the outer peripheral end of the cutting edge 6 and a point P2 on the cutting edge 6 that is 2/3 of the radius from the center and closer to the outer periphery with a straight line. , the distance L (hereinafter referred to as relative distance) from the point P3 of the outer peripheral end of the groove wall 7 facing the cutting edge 6 to the upper perpendicular line is 4 times the diameter of the drill.
Limited to 7% or less.

In addition, since the core thickness ratio is large, the flank surface 8 of the cutting edge 6 is
As shown in the figure, about half of the rear side in the rotating direction of the drill has been ground down by thinning, and the cutting edge 9 of the thick core part has been sharpened.
is formed. The thinning is performed axially symmetrically with respect to the axis O of the drill, so that the cutting face 10 of the cutting edge 9
and an adjacent polisher 11 adjacent thereto are formed.

This kind of thinning is called cross thinning, and the cutting edge 9 of the thick core part is 18 mm from the axis O as shown in Fig. 4.
00 are formed in a straight line on opposite sides. The width of the chisel where the cutting edge 9 is not formed is set within the range of 0III1m to 0.4II1m, and the closer it is to □mm, the better.

In addition, the angle θ2 formed by the direction of the straight line connecting the point P+J3 on the outer periphery p2 of the cutting blade 6 and the axis O and the direction in which the cutting blade 9 in the core thickness section extends is set within the range of 35° to 45°. has been done.

The rake face 10 formed by thinning has an axial rake angle θ. (shown in Figure 7) is -5° to +5°
is set within the range. Further, as shown in FIG. 6, the length of the rake face 10 in the axial direction is Qm at the axial center 0.
m, and increases gradually toward the outside in the radial direction. The angle θ between the valley line 12 formed by the intersection of the rake face 10 and the adjacent polished surface 11 and the axis 0 of the drill is 25° to 60°.
is set within the range. This is set at an angle that ensures a sufficient length in the axial direction of the rake face 10 so that the chips cut by the cutting edge 9 do not hit the adjacent polished surface 11 and increase the thrust. It is set to provide sufficient braking action. In addition, it is set so that sufficient strength can be obtained.

Also, the J angle θ5 between the cutter 10 and the adjacent polished surface 11 is
(shown in FIG. 7) is set within the range of 90° to 1100° to prevent an increase in thrust due to chips and to obtain a sufficient braking action.

FIG. 8 is a perspective view showing an embodiment of the drill in which the tip portion of the drill is configured as described above, and further includes a cutting oil supply hole.

As shown in the figure, inside the ridge portion 3 and the shank 13, which are solid thick portions from the tip to the rear end of the drill, there is a spiral cut along the helix angle of the groove portion 2. Two oil supply holes 14 are formed. The discharge port 115 of each oil supply hole 14 is opened at the flank 8 of the cutting blade 6, and the suction port 16 is opened at the bottom surface 17 of the rear end.

The number of oil supply holes 14 is preferably two, which is equal to the number of grooves 3 formed, but it may be one. Further, the inner diameter of the oil supply hole 14 is desirably several percent to 20% of the diameter of the drill in view of the strength of the drill.

The oil supply hole 14 of this drill is made by forming two holes to serve as oil supply holes along the axial direction in a high-speed steel material formed in a plate-shaped bar member, and then holding the plate-shaped bar member under high temperature. It can be formed by being plastically deformed by twisting.

Furthermore, the drills configured in each of the shapes described above have a surface of the drill having [C,l CN].

The coating layer may be formed of one type or a combination of two or more of TiN and A20e. Further, the coating layer is formed into a dense thin layer by an ion plating method or a chemical vapor deposition method.

Next, the operation of the embodiment of the present invention will be explained based on experimental data in comparison with the conventional example.

The following Table 1 shows 9 drills with a general configuration (conventional product-1), 9 drills with a core thickness ratio simply increased and the groove width ratio decreased to increase strength (conventional product-2), 9 drills according to the present invention ( The data of experiments conducted on three types of sumburu (invention product) are shown.

In addition, in order to make the effect of thinning constant, the same thinning as that of the invention product was applied to all Zambles. The drill diameter is 8.5mm.

Materials are SKI-19 and HRC63. Work material Ha s50 C, Ha 25 OF (T) '), 9J
Cutting conditions C, cutting speed V = 15 m/min, 1 rotation (V) (D feed V) mf = 0.

25111111/ Rotation, drilling depth 40mm.

As is clear from Table 1, the conventional product-2, which has a small groove width ratio and a large core thickness ratio, and the invented product have both increased cross-sectional moment of inertia and torsional rigidity ratio, resulting in increased strength. The effect is remarkable. By the way, although such an effect is well predicted, the reason why a drill like Conventional Product-2 has not been adopted in the prior art is as already stated. Table 1 shows the cutting resistance (1 torque and thrust (
As shown in the data values for thrust), the product of the present invention has a slight increase in thrust, but it is not as good as the conventional product-2, and the torque remains the same as the conventional product-1. Suppressed -C. Moreover, the strength has increased sufficiently. In other words, this is an effect obtained by increasing the radial rake angle of the cutting edge 6.

Another feature of the present invention is that it suppresses deterioration in chip evacuation function. The quality of the chip evacuation function is influenced by the shape of the chips generated and their movement within the groove 2. FIG. 9 is a schematic diagram showing the movement of chips by the drill of conventional product-2.

The chips 18 cut out from the cutting edges 6 and 9 are formed into a curled shape along the groove wall 7 and flow from the center side to the outer circumferential side of the drill. At this time, if the distance between the cutting edge 6 and the groove wall 7 is large, the curl radius of the chip 18 becomes large and the chip 18 becomes 1" if it gets stuck in the groove 2. Also, the chip 18 hits the wall 19 of the hole. One of the important factors governing the movement of the chips 18 is the shape of the cutting edge 6 (the degree of curvature) and the shape of the groove wall 7 (
It is a relative relationship with each other (degree of bending), and therefore,
In order for the chips 18 to pass through the groove 2 and be smoothly discharged, there is an appropriate geometrical relationship between the cutting edge 6 and the groove wall 7. If the shape is expressed by some index, the relative positional relationship of the groove wall 7 to the cutting edge 6 or the cutting edge 6 to the groove wall 7 can be expressed by the distance (relative distance) between them. This is an effective display method. Therefore, by defining the relative distance as one index, it is possible to express the quality of the chip evacuation function by the ratio of the relative path 1l1111 to the drill diameter. That is, the ninth
In the illustrated example, the relative distance [- is large, so that the narrow groove portion 2 cannot fully exhibit the chip discharge function.

FIG. 10 is a schematic diagram showing the movement of chips by the drill of the present invention. Since the relative distance is set to 47% or less of the drill diameter, the chips 18 curl along the groove wall 7, break off into short pieces, and are difficult to flow within the groove 2, that is, easily discharged. formed into a shape.

Further, by setting the angle θ2 shown in FIG. 3 within the range of 35° to 45°, the part of the chip 18 cut by the cutting blade 6 and the part cut by the cutting blade 9 are mutually separated. It is formed in different directions and carved into a shape that is easy to curl and cut. If this angle θ2 is too small, the chips 18 will have a nearly flat shape and will be difficult to curl, and if the chips 18 are scratched, the proportion of the entire portion cut by the cutting blade 9 will be small, making it difficult to curl. Next, the effect when the cutting oil supply hole 14 is formed will be explained. When cutting oil is press-fitted from the suction port 16 of the oil supply hole 14 through the drill holder, the cutting oil passes through the oil supply hole 14 and is supplied to the cutting edge 6 from the discharge port 15 at the tip, effectively cooling the cutting edge by 7 minutes. can do. Further, the returning cutting oil passes through the groove 2 and is discharged to the outside of the hole, and at this time, it promotes the discharge of chips and also cools the workpiece. Therefore, cutting resistance is stabilized and breakage accidents can be prevented.

Furthermore, these drills may be formed only of high-speed steel, but T + C + r + C on the surface of the drill.
N, T+ N and one or two of Ami 20e
By forming a coating layer with a combination of more than one type, the heat resistance of the drill itself can be increased and its wear can be further prevented. Furthermore, since these coating materials have a small coefficient of friction, the thrust and torque can be further reduced.

In addition, when the drill wears out, it is re-sharpened to regenerate the cutting edge, but even if the base material is exposed on the flank 8 of the drill J during this re-sharpening, the outer peripheral surface of the rake face and margin portion The coating layer remains, and the cutting resistance can be maintained at a low level.

[Effects of the Invention] As is clear from the above description, the present invention provides the following excellent effects.

In other words, by increasing the core thickness ratio and decreasing the groove width ratio, the strength of the drill can be increased, and by increasing the radial rake angle of the cutting edge, an increase in cutting resistance can be suppressed, and the relative distance can be reduced. By reducing the thickness, it is possible to suppress the deterioration of the chip evacuation function.

[Brief explanation of the drawing]

Fig. 1 is a side view showing the shape of a conventional drill when viewed directly from the cutting edge end surface, Fig. 2 is a graph showing the relationship between the torsional rigidity ratio, core thickness ratio and groove width ratio of the drill, and Fig. 3 is a side view showing the shape of a conventional drill when viewed directly from the cutting edge. FIG. 4 is a side view showing the shape of a conventional drill when viewed directly from the cutting edge end surface. FIG. 4 is a side view showing the shape when viewed from the cutting edge end surface of an embodiment of the drill of the present invention. FIG. 5 is an embodiment of the drill of the present invention. 6 is a side view taken from the direction of arrow VI in FIG. 5, FIG. 7 is a side view taken from the direction of arrow V [in FIG. 5, and FIG. Figure 59 is a perspective view showing another embodiment of the drill of the present invention, Figure 59 is a schematic diagram showing the movement of chips in a conventional drill, and Figure 10 is a schematic diagram showing the movement of chips in the drill of the present invention. It is a diagram. In addition, in the figure, 1 is the core thickness part, 2 is the groove part, 3 is the cavity part, 6 is the cutting edge, 7 is the groove wall, 9 is the cutting edge of the core thickness part, and 10 is the cutting surface of the cutting edge of the core thickness part. , 11 is the adjacent polished surface, 12 is the valley line, 14 is the oil supply hole, Pl is the outermost point of the cutting edge, P2 is the point on the cutting edge, 2/3 of the radius from the center, near the outer periphery. point, P
, is the outermost point of the groove wall, and gloss is the virtual reference line. Patent applicant: Sumitomo Electric Industries, Ltd. Engraving of the drawing (no changes in content) Figure 1 DI50,20 0.2! ; OJD θJ5 Thickness/Drill f, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, No. 5, Fig. 6, Fig. 7, Centroid, 3 Centroid, Fig. 10. Relationship to the incident Patent applicant address 5-15 Kitahama, Higashi-ku, Osaka City @Place name (
213) Sumitomo Electric Industries, Ltd. Representative: Tetsube Kawakami 4, Agent address: 6, Yachiyo Daiichi Building, 2-3-9 Tenjinbashi, Kita-ku, Osaka, Contents of amendment Drawings and power of attorney 7, Contents of amendment <1) Attach the drawing as attached to the drawing for ￥f4hi. Please note that there are no amendments to the content. (2) The power of attorney will be supplemented as shown in the attached document. Ln:j2 Procedural amendment November 8, 1988 Patent Application No. 33671 2, Title of invention Drill 3, Relationship with the case of the person making the amendment Patent applicant address 5-chome, Kitahama, Higashi-ku, Osaka City Address 15 name (2
13) Sumitomo Electric Industries Co., Ltd. Representative: Tetsube Kawakami 4, Agent Address: 6 Yachiyo Daiichi Pill, 2-3-9 Tenjinbashi, Kita-ku, Osaka, Column for detailed description of the invention in the specification subject to amendment and drawings Contents of the amendment (1) in Figure 4, page 4 of the specification, lines 17 to 18, "If the area is increased, the area of the other/thick part will become smaller" has been changed to "If the area is increased, the area of the other/thick part will be reduced." If you make it smaller, it will be corrected to ``. (2) On page 16 of the specification, line 6, “in other words,” was replaced with “
If it were to be expressed, it would be corrected to ``. (3) Figure 4 of the drawings has been amended as shown in the attached sheet. that's all

Claims (7)

[Claims] (1) A drill made of high-speed steel, where the diameter of the core thickness is set to 25% to 35% of the drill diameter, and the groove width ratio is set within the range of 0.4:1 to 0.8:1. and at least 2 of the drill diameter when viewed directly from the cutting edge end surface.
The rake angle in the radial direction of the cutting edge located on the outer periphery side from /3 is set to -5° to positive, and the point on the outermost periphery of the cutting edge in the shape directly viewed from the cutting edge end and the point on the cutting edge. With respect to a virtual reference line connecting a straight line from the center to a point 2/3 of the radius from the outer periphery, the space of the groove is formed in the cutting blade to a perpendicular line passing through the outermost point of the cutting blade. A drill characterized in that the distance from the outermost point of the groove wall facing apart is set to 47% or less of the drill diameter. (2) In the shape of the cutting edge when viewed directly from the end surface, the cutting edge located on the outer peripheral side of at least 2/3 of the drill diameter is formed into a concave arc so that the rake angle in the radial direction is set to 0° to positive. A drill according to claim 1. (3) The shape of the thick core portion formed by thinning is set so that the chisel width is within the range of Qmm-Q, 4 mm, and in the shape of the cutting edge when viewed directly from the end surface, the thick core portion has a shape that is radially outward from the axis of the thick core portion. The respective cutting edges extending toward each other are formed linearly with respect to each other, and the direction in which the cutting edge of the core thick portion extends and the cutting edge extending further toward the outer periphery from the outer circumferential end of the cutting edge of the core thick portion are formed. Claim 1 or 2, wherein the angle formed by the direction from the outermost peripheral end to the axis is set within a range of 35° to 45°. Drill. (4) The rake face of the cutting edge of the thick core portion formed by thinning has an axial rake angle of 15° to -15°.
, and the length in the axial direction is set to Qmm at the axial center position of the drill. 4. The drill according to claim 3, wherein the drill is formed at an angle of inclination within a range of 25° to 60° with respect to the axis of the drill. (5) The drill according to claim 4, wherein the angle between the rake face of the thick core portion and the adjacent ground surface is set within a range of 90° to 110°. (6) The drill according to claim 1, which has a cutting oil supply hole twisted along a helix angle in the shank from the rear end to the tip of the drill and in the cavity of the main body. (7) Part or all of the surface of the drill, including at least the rake face of the cutting edge and the outer peripheral surface of the margin, is made of Ti.
C, Ti CN, Ti N and △ see. The drill according to claim 1, wherein the drill is coated with one kind or a combination of two or more kinds selected from the group consisting of Oo.