JP2020023051A - Drill - Google Patents

Abstract

To provide a drill which can suppress generation of a long cut scrap.SOLUTION: A drill rotatable around a rotation axis 1 comprises a circular arc-shaped cutting edge 4, and a thinning cutting edge 2. The cutting edge 4 is located on a tip side when viewed from a direction along the rotation axis 1. The thinning cutting edge 2 is positioned on the rotation axis 1 side when viewed from the cutting edge 4 and is continued to the cutting edge 4. A ratio of a length L of the thinning cutting edge 2 to a diameter D of the drill, when viewed from the direction along the rotation axis 1, is not less than 6% and not more than 14%. A ratio of a curvature radius R of the cutting edge 4 to the diameter D of the drill, when viewed from the direction along the rotation axis 1, is not less than 25% and not more than 45%.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a drill applicable to processing of a non-ferrous metal or the like.

  2. Description of the Related Art Conventionally, a drill is known as a tool used for drilling a mechanical part made of metal or the like (for example, see JP-A-2014-83646). Japanese Patent Application Laid-Open No. 2014-83646 discloses a drill used for processing light metal or the like, in which a cutting edge formed on a tip end side of a drill body and a spiral groove for discharging chips are formed. Have been.

JP 2014-83646 A

  When boring a mechanical part using a conventional drill, the length of the generated chips sometimes becomes as long as 3 mm or more. Such long chips may adhere to the machine parts to be machined. For example, when a groove or a recess is formed in advance on the surface of a mechanical component, chips may enter the groove or the recess. In addition, such long chips as described above may be caught in the inside of the groove or the like, and may not be easily discharged from the inside of the groove even if the mechanical parts are washed.

  As described above, when chips are present inside the grooves of the mechanical parts, when assembling the mechanical parts to configure the mechanical device, the mechanical components cannot be assembled or the mechanical device malfunctions. This can cause problems.

  Then, it aims at providing the drill which can suppress generation | occurrence | production of long chip.

  A drill according to one aspect of the present invention is a drill that is rotatable about a rotation axis, and includes an arc-shaped cutting edge and a thinning cutting edge. The cutting edge is disposed on the tip side as viewed from a direction along the rotation axis. The thinning cutting edge is located on the rotating shaft side when viewed from the cutting edge and is connected to the cutting edge. The ratio of the length of the thinning cutting edge to the diameter of the drill as viewed from the direction along the rotation axis is 6% or more and 14% or less. The ratio of the radius of curvature of the cutting edge to the diameter of the drill as viewed from the direction along the rotation axis is 25% or more and 45% or less.

  According to the above, a drill capable of suppressing generation of long chips can be provided.

1 is a schematic perspective view of a drill according to one embodiment of the present invention. FIG. 2 is a schematic diagram of a tip portion viewed from a direction along a rotation axis of the drill shown in FIG. 1. It is the side surface schematic diagram seen from the direction orthogonal to the rotation axis of the drill shown in FIG. It is a schematic diagram of the tip part of the modification of the drill concerning one mode of the present invention. It is a schematic diagram of the tip part of the modification of the drill concerning one mode of the present invention. It is a schematic diagram of the tip part of the modification of the drill concerning one mode of the present invention. It is a schematic diagram of the tip part of the modification of the drill concerning one mode of the present invention. It is the elements on larger scale of the drill shown in FIG. It is a schematic diagram of the tip part of the modification of the drill concerning one mode of the present invention. It is the elements on larger scale of the drill shown in FIG. It is a schematic diagram of the tip part of the modification of the drill concerning one mode of the present invention.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described. In the following description, the same or corresponding elements have the same reference characters allotted, and description thereof will not be repeated.

  (1) A drill 10 according to one embodiment of the present invention is a drill 10 rotatable about a rotation shaft 1, and includes an arc-shaped cutting edge 4 and a thinning cutting edge 2. The cutting edge 4 is disposed on the distal end side as viewed from a direction along the rotation axis 1. The thinning cutting edge 2 is located on the rotating shaft 1 side as viewed from the cutting edge 4 and is connected to the cutting edge 4. The ratio (L / D) of the length L of the thinning cutting edge 2 to the diameter D of the drill 10 as viewed from the direction along the rotation axis 1 is 6% or more and 14% or less. The ratio (R / D) of the radius of curvature R of the cutting edge 4 to the diameter D of the drill 10 as viewed from the direction along the rotation axis 1 is 25% or more and 45% or less.

  With this configuration, by setting the relationship between the length L of the thinning cutting edge 2 and the radius of curvature R of the cutting edge 4 as described above, it is possible to suppress the generation of long chips having a length of 3 mm or more. . Here, the lower limit of the ratio (L / D) of the length L of the thinning cutting edge 2 to the diameter D of the drill 10 is set to 6% for the following reason. That is, if the ratio (L / D) is less than 6%, the strength near the rotation axis of the drill is reduced, so that it becomes difficult to secure the durability of the drill required for practical use. The upper limit of the ratio (L / D) is set to 14% for the following reasons. That is, when the ratio (L / D) exceeds 14%, the chip breaking performance is reduced. Therefore, the probability of occurrence of long chips having a length of 3 mm or more increases in the initial stage of drilling with a drill. As a result, the frequency of occurrence of long chips becomes so high as to cause a problem in practical use.

  The lower limit of the ratio (R / D) of the radius of curvature R of the cutting edge 4 to the diameter D of the drill 10 is set to 25% for the following reason. That is, if the ratio (R / D) is less than 25%, the probability of occurrence of a defect such as chip clogging in a chip discharge groove in a drill increases. The upper limit of the ratio (R / D) is set to 45% for the following reasons. That is, if the ratio (R / D) is more than 45%, the cutting edge 4 cannot give sufficient deformation resistance to the chip, and it becomes difficult to cut the chip with a small curl radius. For this reason, for example, cutting of chips in drilling becomes insufficient. As a result, the probability of generation of long chips is increased.

  (2) In the above drill, when considering a connection point 22 between the arc including the cutting edge 4 and the thinning cutting edge 2 when viewed from the direction along the rotation axis 1, the tangent of the arc at the connection point 22 and the thinning cutting edge 2 may be 110 ° or more and 150 ° or less.

  In this case, by setting the value of the angle α in the above-described range, the chips at the connection between the cutting edge 4 and the thinning cutting edge 2 are not divided, and chips having a substantially constant length as a whole are cut. Can be generated. The lower limit of the angle α is set to 110 ° for the following reason. That is, when the angle α is less than 110 °, the probability of occurrence of long chips in the initial stage of drilling increases. The upper limit of the angle α is set to 150 ° for the following reason. That is, even when the angle α exceeds 150 °, the probability of occurrence of long chips becomes so large as to cause a practical problem.

  (3) In the drill 10, the angle α may be 120 ° or more and 140 ° or less. In this case, the probability of generation of long chips in the initial stage of drilling can be reduced.

  (4) In the drill 10, the ratio (L / D) of the length L of the thinning cutting edge 2 to the diameter D of the drill 10 may be 9% or more and 11% or less. The ratio (R / D) of the radius of curvature R of the cutting edge 4 to the diameter D of the drill 10 may be 30% or more and 35% or less. In this case, the generation probability of long chips can be further reduced.

  (5) The drill 10 may further include a straight portion 21 connecting between the cutting edge 4 and the thinning cutting edge 2. In this case, the cutting of chips at the connection between the cutting edge 4 and the thinning cutting edge 2 can be suppressed.

  (6) The drill may further include a curved portion connecting between the cutting edge and the thinning cutting edge. In this case, the cutting of chips at the connection between the cutting edge 4 and the thinning cutting edge 2 can be suppressed.

[Details of Embodiment of the Present Invention]
Hereinafter, one embodiment of the present disclosure (hereinafter, also referred to as “the present embodiment”) will be described. However, the present embodiment is not limited to these.

<Drill configuration>
As shown in FIGS. 1 to 3, a drill 10 according to the present embodiment is a drill 10 rotatable around a rotating shaft 1, and includes an arc-shaped cutting edge 4, a thinning cutting edge 2, and a spiral cutting edge 2. Groove 8. The torsion angle, which is the intersection angle of the groove 8 with the rotating shaft 1, is, for example, not less than 20 ° and not more than 40 °. The twist angle may be not less than 25 ° and not more than 35 °. As shown in FIG. 2, the cutting edge 4 is disposed on the tip side of the drill 10 as viewed from a direction along the rotation axis 1. In the drill 10 shown in FIGS. 1 to 3, two cutting edges 4 are formed. The number of the cutting edges 4 may be three or more.

  The thinning cutting edge 2 is formed at the tip of the drill 10. The thinning cutting edge 2 is located on the rotating shaft 1 side when viewed from the cutting edge 4. The thinning cutting edge 2 and the cutting edge 4 are formed so as to be continuous via the connecting portion 3. The thinning cutting edge 2 is formed so as to extend from the connection portion 3 toward the rotating shaft 1. The thinning cutting edge 2 is, for example, linear. From a different point of view, the cutting edge 4 is connected to the thinning cutting edge 2 via the connection 3 as an inflection point. Although two thinning cutting edges 2 are formed on the tip side of the drill 10, three or more thinning cutting edges 2 may be formed. Since the cutting edges 4 and the thinning cutting edges 2 are formed so as to be continuous as described above, the number of the cutting edges 4 and the number of the thinning cutting edges 2 are the same.

  The ratio (L / D) of the length L of the thinning cutting edge 2 to the diameter D of the drill 10 as viewed from the direction along the rotation axis 1 is 6% or more and 14% or less. Here, the length L of the thinning cutting edge 2 is a distance from a position of the thinning cutting edge 2 closest to the rotating shaft 1 to the connection portion 3. The ratio (L / D) of the length L of the thinning cutting edge 2 to the diameter D of the drill 10 may be 9% or more and 11% or less.

  As shown in FIG. 2, the ratio (R / D) of the radius of curvature R of the cutting edge 4 to the diameter D of the drill 10 as viewed from the direction along the rotation axis 1 is 25% or more and 45% or less. When the cutting edge 4 includes a portion having a shape different from the arc shape, the radius of curvature R of the cutting edge 4 is the radius of curvature of the arcuate portion of the cutting edge 4. The ratio (R / D) of the radius of curvature R of the cutting edge 4 to the diameter D of the drill 10 may be 30% or more and 35% or less.

  The outer peripheral side of the cutting edge 4 is a flat portion 5 extending along a radial direction which is a direction away from the rotating shaft 1. The rake face of the cutting edge 4 is continuous with the inner peripheral face of the groove 8. The flank 6 adjacent to the cutting edge 4 constitutes a surface on the tip side of the drill 10. An oil hole 7 is formed in a rear surface 9 connected to the flank 6. The inclined surface 11 connected to the rear surface 9 is a surface inclined from the tip side of the drill 10 toward the root side. The inclined surface 11 is continuous with the inner peripheral surface of the groove 8. The position of the thinning cutting edge 2 closest to the rotating shaft 1 is continuous with the boundary line between the rear surface 9 and the inclined surface 11. The boundary line extends linearly in a radial direction away from the rotation axis 1. The boundary extends to the outer periphery of the drill 10.

  When viewed from the direction along the rotation axis 1, the angle α between the tangent of the arc at the connecting portion 3 which is the connection point between the arc including the cutting edge 4 and the thinning cutting edge 2 and the thinning cutting edge 2 is 110 ° or more and 150 ° or more. ° or less. The angle α may be not less than 120 ° and not more than 140 °.

  As shown in FIG. 3, the tip angle θ of the drill 10 can be 140 ° or more and 170 ° or less. The tip angle θ is, for example, 160 °. The diameter D of the drill 10 is, for example, 7.5 mm or less. The diameter D of the drill 10 may be 7 mm or less, or may be 6 mm or less. The diameter D of the drill 10 may be 1 mm or more, or may be 2 mm or more.

<Effects>
In the drill 10 described above, by defining the length L of the thinning cutting edge 2 and the radius of curvature R of the cutting edge 4 as described above, the generation of long chips having a length of 3 mm or more can be suppressed. That is, by setting the ratio (L / D) of the length L of the thinning cutting edge 2 to the diameter D of the drill 10 within the above numerical range, the cutting edge 4 and the thinning cutting edge 2 are consequently formed. The ratio of the thinning cutting edge 2 in the entire blade is relatively reduced. As a result, it is possible to improve the chip breaking performance. Further, by setting the ratio (R / D) of the radius of curvature R of the cutting edge 4 to the diameter D of the drill 10 within the above-mentioned numerical range, the radius of curvature R of the cutting edge 4 can be made smaller than before. I have. Therefore, the chips can be deformed and the chips can be cut with a small curl radius.

  Also, by setting the value of the angle α shown in FIG. 2 in the above range, the chips are not divided at the connection portion 3 between the cutting edge 4 and the thinning cutting edge 2, and as a whole from the beginning of drilling. Almost constant length chips can be produced.

<Configuration and Operation and Effect of Modification>
4 to 11 show modified examples of the drill 10 according to the present embodiment. 4 to 7, FIG. 9, and FIG. 11 correspond to FIG.

  The drill 10 shown in FIG. 4 basically has the same configuration as the drill 10 shown in FIGS. 1 to 3, but the shape of the boundary line between the rear surface 9 and the inclined surface 11 and the position of the oil hole 7 are not shown. It differs from the drill 10 shown in FIGS. That is, in the drill 10 shown in FIG. 4, the boundary between the rear surface 9 and the inclined surface 11 is curved. The boundary line is a curved line protruding toward the rear surface 9. The boundary extends to the outer peripheral portion of the drill 10. The oil hole 7 is formed so as to overlap a boundary line between the rear surface 9 and the inclined surface 11. From a different viewpoint, the oil hole 7 is formed so as to extend over both the rear surface 9 and the inclined surface 11. With the drill 10 having such a configuration, the same effect as the drill 10 shown in FIGS. 1 to 3 can be obtained.

  The drill 10 shown in FIG. 5 basically has the same configuration as the drill 10 shown in FIGS. 1 to 3, but the shape of the boundary between the rear surface 9 and the inclined surface 11 and the position of the oil hole 7 are not shown. It differs from the drill 10 shown in FIGS. That is, in the drill 10 shown in FIG. 5, the boundary between the rear surface 9 and the inclined surface 11 is constituted by an arc-shaped portion and a linear portion. The boundary line is a curved line protruding toward the rear surface 9. The boundary line is connected to the groove 8 at the end opposite to the rotation shaft 1. That is, the boundary does not extend to the outer peripheral portion of the drill 10. The oil hole 7 is formed so as to overlap a boundary line between the rear surface 9 and the inclined surface 11. With the drill 10 having such a configuration, the same effect as the drill 10 shown in FIGS. 1 to 3 can be obtained.

  The drill 10 shown in FIG. 6 basically has the same configuration as the drill 10 shown in FIGS. 1 to 3, but the position of the oil hole 7 and the shape of the cutting edge 4 are shown in FIGS. 1 to 3. Different from drill 10. That is, in the drill 10 shown in FIG. 6, the oil hole 7 is formed so as to overlap the boundary between the rear surface 9 and the inclined surface 11. In the drill 10 shown in FIG. 6, the flat portion 5 (see FIG. 2) is not formed in a portion of the cutting edge 4 on the outer peripheral side away from the rotation shaft 1. That is, in the drill 10 shown in FIG. 6, the arc-shaped cutting edge 4 extends to the outer peripheral portion of the drill 10. With the drill 10 having such a configuration, the same effect as the drill 10 shown in FIGS. 1 to 3 can be obtained.

  The drill 10 shown in FIGS. 7 and 8 basically has the same configuration as the drill 10 shown in FIGS. 1 to 3, but the shape of the connecting portion between the cutting edge 4 and the thinning cutting edge 2 and the oil hole The position of 7 differs from the drill 10 shown in FIGS. That is, in the drill 10 shown in FIGS. 7 and 8, a straight portion 21 that connects the cutting edge 4 and the thinning cutting edge 2 is formed at a connection portion between the cutting edge 4 and the thinning cutting edge 2. The oil hole 7 is formed so as to overlap the boundary between the rear surface 9 and the inclined surface 11. With the drill 10 having such a configuration, the same effect as the drill 10 shown in FIGS. 1 to 3 can be obtained.

  When such a straight portion 21 is formed, the length L of the thinning cutting edge 2 is defined as follows. That is, a virtual connection point 22 between the arc including the cutting edge 4 and the thinning cutting edge 2 when viewed from the direction along the rotation axis 1 is considered. The distance from the position closest to the rotating shaft 1 to the connection point 22 in the thinning cutting edge 2 is defined as the length L of the thinning cutting edge 2.

  The drill 10 shown in FIGS. 9 and 10 basically has the same configuration as the drill 10 shown in FIGS. 7 and 8, but the shape of the connecting portion between the cutting edge 4 and the thinning cutting edge 2 is the same as that shown in FIGS. And a drill 10 shown in FIG. That is, in the drill 10 shown in FIGS. 9 and 10, a curved portion 23 that connects the cutting edge 4 and the thinning cutting edge 2 is formed at a connection portion between the cutting edge 4 and the thinning cutting edge 2. With the drill 10 having such a configuration, the same effect as that of the drill 10 shown in FIGS. 7 and 8 can be obtained.

  When such a curved portion 23 is formed, the length L of the thinning cutting edge 2 is defined as follows. That is, as in the case of the drill 10 shown in FIGS. 7 and 8, a virtual connection point 22 between the arc including the cutting edge 4 and the thinning cutting edge 2 when viewed from the direction along the rotation axis 1 is considered. The distance from the position closest to the rotating shaft 1 to the virtual connection point 22 on the thinning cutting edge 2 is defined as the length L of the thinning cutting edge 2.

  The drill 10 shown in FIG. 11 basically has the same configuration as the drill 10 shown in FIGS. 1 to 3, but is different from the drill 10 shown in FIGS. 1 to 3 in that an oil hole is not formed. Is different. That is, in the drill 10 shown in FIG. 11, no oil hole is formed in the rear surface 9. With the drill 10 having such a configuration, the same effect as the drill 10 shown in FIGS. 1 to 3 can be obtained.

<Example>
The following experiment was performed to confirm the effect of the present embodiment.

1) Sample The configuration shown in FIGS. 1 to 3 was used, in which the length L of the thinning cutting edge 2, the radius of curvature R of the cutting edge 4, and the angle α between the cutting edge 4 and the thinning cutting edge 2 were changed. Eighteen kinds of drills were prepared as samples. The drill diameter D of each sample was 5.5 mm. The material of the drill was DL1300 (DLC coating). The tip angle θ of the drill was 160 °. The torsion angle of the groove 8 of the drill was 25 °.

2) Experimental method A plate material made of an aluminum alloy equivalent to ADC12 was prepared as a work material. The thickness of the plate was 20 mm. Drilling was performed on this work material using a drill for each sample until the set life was reached, and the generation ratio of long chips at this time was measured. Note that chips having a length of 3 mm or more were measured as long chips.

  As cutting conditions, the cutting speed Vc was 170 mm / sec, and the feed amount f was 0.9 mm / rev. The coolant was supplied via an oil hole as the supply condition, and the supply pressure was 2 MPa. The coolant was an emulsion type and was used at a 20-fold dilution.

3) Results Table 1 shows sample conditions and experimental results.

  In Table 1, in the column of the thinning cutting edge length L, the ratio of the length L of the thinning cutting edge (unit: mm) and the length L of the thinning cutting edge to the diameter D (unit: mm) of the drill ( L / D). For example, the sample No. The indication of 0.275 (5%) in the column of the thinning cutting edge length L of 1 indicates that the length L of the thinning cutting edge is 0.275 mm and the ratio (L / D) is 5%. ing.

  In the column of the radius R of curvature of the cutting edge in Table 1, the radius of curvature R (unit: mm) of the cutting edge 4 and the ratio (R) of the radius of curvature R of the cutting edge 4 to the diameter D (unit: mm) of the drill are shown. / D). For example, the sample No. R1.9 (35%) in the column of the cutting edge radius of curvature R of 1 indicates that the radius of curvature R is 1.9 mm and the ratio (R / D) is 35%.

  In the column of the contact angle in Table 1, the value of the angle α between the cutting edge 4 and the thinning cutting edge 2 shown in FIG. 2 is described. In the column of the chip generation ratio of 3 mm or more, the initial column shows the chip generation ratio of 3 mm or more at the initial stage of drilling (up to the point when 100 holes are drilled). . In the column of the set life, the generation rate of chips having a length of 3 mm or more up to the time when drilling of 10,000 holes as the set life is shown. In addition, here, as for the generation ratio of chips having a length of 3 mm or more, the acceptance criterion was 5% or less.

  As shown in Table 1, the sample No. which is out of the range of the present embodiment. With respect to 1, 6, 7, 12, 13, and 18, the rate of occurrence of long chips exceeds 5%, clogging of chips occurs and evaluation cannot be performed, or breakage in the middle cannot be evaluated and evaluation cannot be performed. did. On the other hand, the sample No. corresponding to the present embodiment. With respect to 2 to 5, 8 to 11, and 14 to 17, the generation ratio of long chips was 5% or less, which satisfied the standard. Further, the sample No. As for 3, 4, 9, 10, 15, and 16, the generation rate of particularly long chips was low. Thus, it was shown that the generation of long chips was suppressed in the sample corresponding to the present embodiment.

  It should be understood that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the embodiments described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The invention is particularly advantageously applied to drilling of workpieces.

DESCRIPTION OF SYMBOLS 1 Rotation axis 2 Thinning cutting edge 3 Connection part 4 Cutting edge 5 Flat part 6 Flank surface 7 Oil hole 8 Groove 9 Rear surface 10 Drill 11 Inclined surface 21 Linear part 22 Connection point 23 Curved surface part

Claims (4)

A drill rotatable about a rotation axis,
An arc-shaped cutting edge arranged on the tip side as viewed from a direction along the rotation axis,
A thinning cutting edge that is located on the rotating shaft side as viewed from the cutting edge and is continuous with the cutting edge,
A ratio of a length of the thinning cutting edge to a diameter of the drill, viewed from a direction along the rotation axis, of 9% or more and 11% or less;
A ratio of a radius of curvature of the cutting edge to a diameter of the drill, as viewed from a direction along the rotation axis, is 30% or more and 35% or less;
When considering the connection point between the arc including the cutting edge and the thinning cutting edge viewed from the direction along the rotation axis, the angle between the tangent of the arc at the connection point and the thinning cutting edge is 120 ° or more and 140 ° or less,
The diameter of the drill is 1 mm or more and 7.5 mm or less,
As a work material, when a plate material made of an aluminum alloy having a thickness of 20 mm is drilled at a cutting speed of 170 mm / sec and a feed amount of 0.9 mm / rev, the length of chips by the drill becomes less than 3 mm. ,Drill. The tip angle of the drill is 160 °,
An oil hole is provided on a rear surface connected to the flank adjacent to the cutting edge,
2. The drill according to claim 1, wherein the drilling further supplies an emulsion type coolant at a supply pressure of 2 MPa through the oil hole. 3.   3. The drill according to claim 1, further comprising a straight portion connecting between the cutting edge and the thinning cutting edge. 4.   The drill according to claim 1 or 2, further comprising a curved portion connecting the cutting edge and the thinning cutting edge.

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