JP2017164836A - drill - Google Patents

Abstract

A drill capable of suppressing generation of long chips is provided.
A drill that is rotatable about a rotary shaft 1 and includes an arcuate cutting edge 4 and a thinning cutting edge 2. The cutting edge 4 is disposed on the tip side viewed from the direction along the rotation axis 1. The thinning cutting edge 2 is located on the rotating shaft 1 side when viewed from the cutting edge 4 and is continuous with the cutting edge 4. The ratio of the length L of the thinning cutting edge 2 to the diameter D of the drill as viewed from the direction along the rotation axis 1 is 6% or more and 14% or less. The ratio of the curvature radius R of the cutting edge 4 to the diameter D of the drill as viewed from the direction along the rotation axis 1 is 25% or more and 45% or less.
[Selection] Figure 2

Description

  The present invention relates to a drill applicable to processing of a nonferrous metal or the like.

  Conventionally, a drill is known as a tool used for drilling a machine part made of metal or the like (see, for example, 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 drill formed on a tip side of a drill body and a spiral groove for discharging chips is disclosed. Has been.

JP 2014-83646 A

  When drilling a machine part using a conventional drill, the length of the generated chips may be as long as 3 mm or more, for example. Such a long chip may adhere to a machine part to be processed. 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. The long chips as described above may be caught inside the groove or the like, and may not be easily discharged from the inside of the groove even if the machine part is cleaned.

  In this way, when there are chips inside the groove of the machine part, when assembling the machine part to configure the machine apparatus, the machine part cannot be assembled or malfunction of the machine apparatus occurs. Cause problems.

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

  The drill which concerns on 1 aspect of this invention is a drill which can rotate centering around a rotating shaft, Comprising: An arc-shaped cutting edge and a thinning cutting edge are provided. The cutting edge is disposed on the tip side viewed from the direction along the rotation axis. The thinning cutting edge is located on the rotating shaft side when viewed from the cutting edge and is continuous with the cutting edge. The ratio of the length of the thinning cutting edge to the diameter of the drill 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 viewed from the direction along the rotation axis is 25% or more and 45% or less.

  According to the above, it is possible to provide a drill capable of suppressing the generation of long chips.

It is a perspective schematic diagram of a drill concerning one mode of the present invention. It is the schematic diagram of the front-end | tip part seen from the direction along the rotating shaft of the drill shown in FIG. It is the side surface schematic diagram seen from the direction orthogonal to the rotating shaft of the drill shown in FIG. It is a schematic diagram of the front-end | tip part of the modification of the drill which concerns on 1 aspect of this invention. It is a schematic diagram of the front-end | tip part of the modification of the drill which concerns on 1 aspect of this invention. It is a schematic diagram of the front-end | tip part of the modification of the drill which concerns on 1 aspect of this invention. It is a schematic diagram of the front-end | tip part of the modification of the drill which concerns on 1 aspect of this invention. FIG. 8 is a partially enlarged schematic view of the drill shown in FIG. 7. It is a schematic diagram of the front-end | tip part of the modification of the drill which concerns on 1 aspect of this invention. FIG. 10 is a partially enlarged schematic view of the drill shown in FIG. 9. It is a schematic diagram of the front-end | tip part of the modification of the drill which concerns on 1 aspect of this 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 are denoted by the same reference numerals, and the same description is not repeated.

  (1) The drill 10 which concerns on 1 aspect of this invention is the drill 10 which can rotate centering on the rotating shaft 1, Comprising: The circular arc-shaped cutting edge 4 and the thinning cutting edge 2 are provided. The cutting edge 4 is disposed on the tip side viewed from the direction along the rotation axis 1. The thinning cutting edge 2 is located on the rotating shaft 1 side when viewed from the cutting edge 4 and is continuous with 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.

  If it does in this way, generation | occurrence | production of the long chip | tip with a length of 3 mm or more can be suppressed by setting the relationship between the length L of the thinning cutting edge 2 and the curvature radius R of the cutting edge 4 as mentioned above. . Here, the reason why 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% is as follows. That is, if the ratio (L / D) is less than 6%, the strength in the vicinity of the rotation axis of the drill decreases, and as a result, it is difficult to ensure the durability of the drill that is practically required. The reason why the upper limit of the ratio (L / D) is set to 14% is as follows. That is, when the ratio (L / D) exceeds 14%, the chip breaking property is reduced. Therefore, at the initial stage of drilling with a drill, the generation probability of long chips having a length of 3 mm or more is increased. As a result, the occurrence frequency of long chips becomes high enough to cause a practical problem.

  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 the chip discharge groove in the drill increases. The reason why the upper limit of the ratio (R / D) is set to 45% is as follows. That is, when the ratio (R / D) exceeds 45%, it is difficult to give sufficient deformation resistance to the chips by the cutting blade 4, and it becomes difficult to cut the chips with a small curl radius. For this reason, for example, cutting of chips in drilling is insufficient. As a result, the occurrence probability of long chips increases.

  (2) When considering the 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 in the drill, the arc tangent and the thinning cutting edge at the connection point 22 The angle α between 2 and 110 may be 110 ° or more and 150 ° or less.

  In this case, by setting the value of the angle α in the above range, the chips are not divided at the connecting portion between the cutting edge 4 and the thinning cutting edge 2, and the chips having a substantially constant length as a whole are formed. 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 generation probability of long chips at 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 large enough to cause a practical problem.

  (3) In the drill 10, the angle α may be not less than 120 ° and not more than 140 °. In this case, it is possible to reduce the occurrence probability of long chips at the initial stage of drilling.

  (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 linear portion 21 that connects between the cutting edge 4 and the thinning cutting edge 2. In this case, the cutting of chips at the connecting portion 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 connecting portion between the cutting edge 4 and the thinning cutting edge 2 can be suppressed.

[Details of the embodiment of the present invention]
Hereinafter, an embodiment of the present disclosure (hereinafter also referred to as “the present embodiment”) will be described. However, this 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 that can rotate around a rotating shaft 1, and has an arcuate cutting edge 4, a thinning cutting edge 2, and a spiral shape. The groove 8 is provided. The torsion angle that is the crossing angle of the groove 8 with respect to the rotating shaft 1 is, for example, 20 ° to 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 the 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 cutting edges 4 may be 3 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 connection portion 3. The thinning cutting edge 2 is formed so as to extend from the connecting portion 3 to the rotating shaft 1 side. The thinning cutting edge 2 is linear, for example. Speaking from a different point of view, the cutting edge 4 is connected to the thinning cutting edge 2 via a connecting portion 3 as an inflection point. Although two thinning cutting edges 2 are formed on the distal end side of the drill 10, three or more thinning cutting edges 2 may be formed. Since the cutting edge 4 and the thinning cutting edge 2 are formed 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 the distance from the position closest to the rotating shaft 1 to the connecting portion 3 in the thinning cutting edge 2. 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 curvature radius R of the cutting edge 4 is the curvature radius 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 that is a direction away from the rotary shaft 1. The rake face of the cutting edge 4 is continuous with the inner peripheral face of the groove 8. Further, 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 the rear surface 9 that continues 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 closest to the rotary shaft 1 in the thinning cutting edge 2 described above is continuous with the boundary line between the rear surface 9 and the inclined surface 11. The boundary line extends linearly toward the radial direction away from the rotating shaft 1. The boundary line extends to the outer periphery of the drill 10.

  The angle α between the tangent of the arc at the connecting portion 3, which is a connection point 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 110 ° to 150 °. ° 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 set to 140 ° or more and 170 ° or less. The tip angle θ is 160 °, for example. 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 6 mm or less. The diameter D of the drill 10 may be 1 mm or more, or 2 mm or more.

<Effect>
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, 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 numerical range as described above, the cutting edge 4 and the thinning cutting edge 2 are consequently formed. The ratio of the thinning cutting edge 2 in the whole blade is relatively small. As a result, the chip breaking property can be improved. 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 numerical range as described above, as a result, the curvature radius R of the cutting edge 4 is made smaller than before. Yes. For this reason, it is possible to deform the chips and cut the chips with a small curl radius.

  Moreover, 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 from the beginning of the drilling process as a whole. Chips of almost constant length can be generated.

<Configuration and effect of modification>
4 to 11 show modifications of the drill 10 according to the present embodiment. 4 to 7, 9, and 11 correspond to FIG. 2, respectively.

  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 illustrated. 1 to 3 different from the drill 10 shown in FIG. That is, in the drill 10 shown in FIG. 4, the boundary line between the rear surface 9 and the inclined surface 11 is curved. The boundary line is a convex curve on the rear surface 9 side. Further, the boundary line extends to the outer peripheral portion of the drill 10. The oil hole 7 is formed so as to overlap the boundary line between the rear surface 9 and the inclined surface 11. From a different point of view, the oil hole 7 is formed so as to extend over both the rear surface 9 and the inclined surface 11. Also 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 line between the rear surface 9 and the inclined surface 11 and the position of the oil hole 7 are illustrated. 1 to 3 different from the drill 10 shown in FIG. That is, in the drill 10 shown in FIG. 5, the boundary line 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 convex curve on the rear surface 9 side. The boundary line is connected to the groove 8 at the end opposite to the rotary shaft 1 side. That is, the boundary line does not extend to the outer peripheral portion of the drill 10. The oil hole 7 is formed so as to overlap the boundary line between the rear surface 9 and the inclined surface 11. Also 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. Different from the drill 10. That is, in the drill 10 shown in FIG. 6, the oil hole 7 is formed so as to overlap the boundary line between the rear surface 9 and the inclined surface 11. Moreover, in the drill 10 shown in FIG. 6, the flat part 5 (refer FIG. 2) is not formed in the part of the outer peripheral side away from the rotating shaft 1 in the cutting blade 4. FIG. That is, in the drill 10 shown in FIG. 6, the arcuate cutting edge 4 extends to the outer peripheral portion of the drill 10. Also 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. 7 is different 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 between the cutting edge 4 and the thinning cutting edge 2 is formed at the 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 line between the rear surface 9 and the inclined surface 11. Also with the drill 10 having such a configuration, the same effect as the drill 10 shown in FIGS. 1 to 3 can be obtained.

  In addition, when such a linear part 21 is formed, the length L of the thinning cutting edge 2 is prescribed | regulated as follows. That is, a virtual connection point 22 between the arc including the cutting edge 4 and the thinning cutting edge 2 as 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 as shown in FIG. And the drill 10 shown in FIG. That is, in the drill 10 shown in FIGS. 9 and 10, a curved portion 23 that connects between the cutting edge 4 and the thinning cutting edge 2 is formed at the connection portion between the cutting edge 4 and the thinning cutting edge 2. Also with the drill 10 having such a configuration, the same effect as the drill 10 shown in FIGS. 7 and 8 can be obtained.

  In addition, when such a curve part 23 is formed, the length L of the thinning cutting edge 2 is prescribed | regulated 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 in 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, except that the oil hole is not formed. Is different. That is, in the drill 10 shown in FIG. 11, no oil hole is formed on the rear surface 9. Also 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>
In order to confirm the effect of this embodiment, the following experiment was conducted.

1) Sample In the configuration shown in FIGS. 1 to 3, 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 types of drills were prepared as samples. In each sample, the diameter D of the drill was set to 5.5 mm. The material of the drill was DL1300 (DLC coat). The tip angle θ of the drill was 160 °. The twist 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 plate material had a thickness of 20 mm. This work material was drilled to the set life using the drill of each sample, and the generation rate 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 set to 170 mm / sec, and the feed amount f was set to 0.9 mm / rev. The coolant was supplied through an oil hole, 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 the sample conditions and experimental results.

  In Table 1, in the column of the thinning cutting edge length L, the length L (unit: mm) of the thinning cutting edge and the ratio of the length L of the thinning cutting edge to the diameter D (unit: mm) of the drill ( L / D). For example, sample No. The display of 0.275 (5%) in the column of 1 thinning cutting edge length L 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 cutting edge curvature radius R in Table 1, the curvature radius R (unit: mm) of the cutting edge 4 and the ratio of the curvature radius R of the cutting edge 4 to the diameter D (unit: mm) of the drill (R) / D). For example, sample No. R1.9 (35%) in the column of 1 cutting edge curvature radius R indicates that the curvature radius R is 1.9 mm and the ratio (R / D) is 35%.

  Further, in the contact angle column of 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. Of the columns of the chip generation ratio of 3 mm or more, the initial column indicates the chip generation ratio of 3 mm or more in the initial stage of the drilling process (up to the point when the 100 holes are drilled). . Further, the set life column shows the generation rate of chips having a length of 3 mm or more up to the point of time when 10000 holes are drilled as the set life. In addition, about 5% or less was used as a pass criterion for the generation ratio of chips having a length of 3 mm or more.

  As shown in Table 1, No. 1, which is a sample outside the range of the present embodiment. For 1, 6, 7, 12, 13, and 18, the generation rate of long chips exceeds 5%, clogging of chips occurs, and evaluation cannot be performed due to breakage in the middle. did. On the other hand, the sample corresponding to this embodiment is No. About 2-5, 8-11, 14-17, the generation | occurrence | production ratio of the long chip | tip was all 5% or less, and satisfy | filled the reference | standard. Furthermore, sample no. For 3, 4, 9, 10, 15, and 16, the generation ratio of particularly long chips was low. Thus, it was shown that generation of long chips can be suppressed in the sample corresponding to the present embodiment.

  The embodiment disclosed this time is to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

  The present invention is particularly advantageously applied to drilling a work material.

DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Thinning cutting edge 3 Connection part 4 Cutting edge 5 Flat part 6 Relief surface 7 Oil hole 8 Groove 9 Rear surface 10 Drill 11 Inclined surface 21 Straight line part 22 Connection point 23 Curved surface part

Claims (6)

A drill that is rotatable about a rotation axis,
An arcuate cutting edge disposed on the tip side seen from the direction along the rotation axis;
A thinning cutting edge located on the rotary shaft side as viewed from the cutting edge and connected to the cutting edge;
The ratio of the length of the thinning cutting edge to the diameter of the drill as seen from the direction along the rotation axis is 6% or more and 14% or less,
The drill whose ratio of the curvature radius of the cutting edge to the diameter of the drill seen from the direction along the rotation axis is 25% or more and 45% or less.   When considering the connection point between the arc including the cutting edge and the thinning cutting edge as 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 The drill according to claim 1 which is 110 degrees or more and 150 degrees or less.   The drill according to claim 2, wherein the angle is not less than 120 ° and not more than 140 °. The ratio of the length of the thinning cutting edge to the diameter of the drill is 9% or more and 11% or less,
The drill according to any one of claims 1 to 3, wherein the ratio of the radius of curvature of the cutting edge to the diameter of the drill is 30% or more and 35% or less.   The drill according to any one of claims 1 to 4, further comprising a linear portion that connects between the cutting edge and the thinning cutting edge.   The drill according to any one of claims 1 to 4, further comprising a curved portion that connects between the cutting edge and the thinning cutting edge.

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