Dust collection drilling bit

Abstract

To increase efficiency of drilling work by preventing the occurrence of such a problem that foreign matter blocks a dust suction port in a dust collection drilling bit.SOLUTION: A drilling bit is provided, comprising a bit shaft portion and a bit distal end portion having a cutting edge portion. The bit shaft portion includes: an axial dust collection passage extending in an axial direction; a radial dust collection passage which is communicated with the axial dust collection passage and opens outward in a radial direction, and has a dust collection port opened outward in a radial direction perpendicular to the axial direction; and a dust guide groove which is provided on an outer peripheral surface of the bit shaft portion, and in which the dust collection port is disposed, the dust guide groove having an introduction opening which opens on a distal end side in the axial direction. A distance in the radial direction between a first virtual circle placed around the axis of the bit shaft portion and passing through an outer end in the radial direction of the cutting edge portion when viewed from the distal end side in the axial direction, and an inner end in the radial direction of the introduction opening, is shorter than a diameter of a second virtual circle with the largest area among virtual circles included in the dust collection port when viewed from the radial direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to dust-vacuuming drill bits. [Background technology]

[0002] Patent Document 1 discloses a dust-suction drill bit. The dust-suction drill bit includes a bit shaft portion and a bit tip portion provided on the axial tip side of the bit shaft portion and having a cutting edge portion. The bit shaft portion includes an axial dust-suction passage extending in the axial direction. The bit tip portion has a surface facing the axial tip side. The surface is provided with a dust-suction port communicating with the axial dust-suction passage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6691484 Summary of the Invention [Problem to be solved by the invention]

[0004] In the dust-collecting drill bit, the dust generated by cutting the workpiece during the drilling operation is sucked in through the dust suction port, so that the efficiency of the drilling operation can be improved. However, in the dust-collecting drill bit, there are cases where the dust suction port is blocked by foreign objects, and the efficiency of the drilling operation cannot be improved.

[0005] Therefore, an object of the present disclosure is to prevent foreign matter from clogging the dust suction port of a dust-collecting drill bit and to improve the efficiency of drilling operations. [Means for solving the problem]

[0006] A dust-suction drill bit according to one embodiment of the present disclosure is a drill bit including a bit shaft portion and a bit tip portion provided on the axial tip side of the bit shaft portion and having a cutting blade portion, wherein the bit shaft portion includes an axial dust-suction passage extending in the axial direction, a radial dust-suction passage communicating with the axial dust-suction passage and having a dust suction port opening radially outwardly perpendicular to the axial direction, and a dust guide groove provided on the outer circumferential surface of the bit shaft portion and in which the dust suction port is disposed, the dust guide groove having an introduction opening opening on the tip side in the axial direction, wherein the radial distance between a first virtual circle centered on the axis of the bit shaft portion and passing through the radial outer end of the cutting blade portion and the radial inner end of the introduction opening is shorter than the diameter of a second virtual circle having the largest area among the virtual circles contained in the dust suction port when viewed from the radial direction.

[0007] According to one aspect of the present disclosure, dust generated by the cutting blade cutting the workpiece during drilling operation enters the dust guide groove from the introduction opening, passes through the dust guide groove, and is sucked into the dust suction port. The radial distance between the first virtual circle showing the rotation trajectory of the radial outer end of the cutting blade and the radial inner end of the introduction opening is shorter than the diameter of the second virtual circle with the largest area among the virtual circles contained in the dust suction port when viewed from the radial direction, so that foreign matter that may block the dust suction port is unlikely to pass through the introduction opening of the dust guide groove. Therefore, it is possible to prevent foreign matter from blocking the dust suction port, and to improve the efficiency of the drilling operation while suctioning dust.

[0008] A dust-suction drill bit according to another embodiment of the present disclosure is a drill bit including a bit shaft portion and a bit tip portion provided on the axial tip side of the bit shaft portion and having a cutting blade portion, wherein the bit shaft portion includes an axial dust-suction passage extending in the axial direction, a radial dust-suction passage communicating with the axial dust-suction passage and having a dust suction port opening radially outwardly perpendicular to the axial direction, and a dust guide groove provided on the outer circumferential surface of the bit shaft portion and in which the dust suction port is disposed, the dust guide groove having an introduction opening opening on the tip side in the axial direction, wherein when viewed from the tip side in the axial direction, the radial distance between a first virtual circle centered on the axis of the bit shaft portion and passing through the radial outer end of the cutting blade portion and the radial inner end of the introduction opening is smaller than the width dimension of the dust guide groove at the introduction opening.

[0009] According to another aspect of the present disclosure, dust generated by the cutting blade cutting the workpiece during drilling enters the dust guide groove from the introduction opening, passes through the dust guide groove, and is sucked into the dust suction port. The radial distance between the first virtual circle showing the rotation trajectory of the radial outer end of the cutting blade and the radial inner end of the introduction opening is smaller than the width dimension of the dust guide groove at the introduction opening, so that foreign matter that may block the dust suction port is unlikely to pass through the introduction opening of the dust guide groove. Therefore, it is possible to prevent foreign matter from blocking the dust suction port, and to improve the efficiency of drilling while suctioning dust. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a dust-vacuum drill bit according to an embodiment, an electric drill device connected to the dust-vacuum drill bit, and a suction device connected to the dust-vacuum drill bit via a hose. [Diagram 2] FIG. 2 is a schematic diagram of the dust-vacuum drill bit of FIG. 1 attached to an adapter. [Diagram 3] FIG. 3 is a view showing a part of the dust-vacuum drill bit of FIG. 2, showing the bit tip and its surrounding area from a radial direction. [Figure 4]FIG. 4 is a view of the dust-vacuum drill bit of FIG. 3 as viewed from the tip end side in the axial direction. [Diagram 5] FIG. 5 is a view of a part of the dust-suction drill bit according to the first modified example, showing the dust suction port and its surrounding area as viewed from a radial direction. [Figure 6A] FIG. 6A is a perspective view of a part of a dust-vacuum drill bit according to a second modified example, showing a bit tip and its surrounding area. [Figure 6B] FIG. 6B is a view of the dust-vacuum drill bit of FIG. 6A as viewed from the tip end side in the axial direction. [Figure 7] FIG. 7 is a view of a dust-vacuuming drill bit according to a third modified example, as viewed from the tip side in the axial direction. [Figure 8] FIG. 8 is a view of a dust-vacuuming drill bit according to a fourth modified example, as viewed from the tip side in the axial direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment will be described with reference to the drawings. In the following description, the direction in which the axis AX of the dust-vacuum drill bit 1A extends is defined as the axial direction, the direction perpendicular to the axial direction is defined as the radial direction, and the direction around the axial direction is defined as the circumferential direction.

[0012] FIG. 1 is a schematic diagram showing a dust-vacuum drill bit 1A according to an embodiment, an electric drill device 80 connected to the dust-vacuum drill bit 1A, and a suction device 90 connected to the dust-vacuum drill bit 1A via a hose 88.

[0013] As shown in Fig. 1, the dust-vacuum drill bit 1A is connected to an electric drill device 80 by having its base end portion, that is, shank portion 50 (see Fig. 2), held by a holding portion 81 of the electric drill device 80. An adapter 70 is attached to a supported portion 55 (see Fig. 2), that is a central portion of the dust-vacuum drill bit 1A. The adapter 70 surrounds the supported portion 55 when viewed from the axial direction, and rotatably supports the supported portion 55. A connection port 78 of the adapter 70 is connected to a suction port 98 of a suction device 90 via a hose 88.

[0014] When the switch 82 of the electric drill 80 is pressed by an operator, the dust-collecting drill bit 1A is driven by a drive device provided in a housing 83 of the electric drill 80, so that the dust-collecting drill bit 1A rotates around the axis and vibrates along the axis. In this state, the bit tip 10 (see Figs. 2 to 4), which is the tip of the dust-collecting drill bit 1A, is pressed against the workpiece P to perform drilling work on the workpiece P. At this time, by driving the suction device 90, dust generated by cutting the workpiece P is sucked in through the dust suction port 33 (see Figs. 2 and 3) provided at the tip of the dust-collecting drill bit 1A, and is guided to the suction device 90 via the adapter 70 and the hose 88. In this manner, drilling work can be performed on the workpiece P while suctioning dust.

[0015] Fig. 2 is a schematic diagram of the dust-vacuum drill bit 1A of Fig. 1 attached to an adapter 70. As shown in Fig. 2, the dust-vacuum drill bit 1A includes a bit shaft portion 30 and a bit tip portion 10 provided on the axial tip side of the bit shaft portion 30.

[0016] The bit shaft portion 30 has a shaft tip portion 31 located at the tip side in the axial direction, a shank portion 50 located at the base end side in the axial direction, and a supported portion 55 located between the shaft tip portion 31 and the shank portion 50. The shaft tip portion 31, the shank portion 50, and the supported portion 55 are coaxial with one another and are integral.

[0017] The bit shaft portion 30 has an axial dust suction passage 60 extending in the axial direction. The axial dust suction passage 60 extends in the axial direction from the tip portion of the shaft tip portion 31 to the center portion of the supported portion 55. The supported portion 55 has a base end dust suction passage 57 that communicates with the axial dust suction passage 60 and extends in the radial direction. The adapter 70 has an adapter dust suction passage 71 that communicates with the base end dust suction passage 57 and extends in the radial direction. The end of the adapter dust suction passage 71 opposite the base end dust suction passage 57 is a connection port 78 of the adapter 70.

[0018] Fig. 3 is a view of a part of the dust-suction drill bit 1A of Fig. 2, showing the bit tip 10 and its surroundings from the radial direction. Fig. 4 is a view of the dust-suction drill bit 1A of Fig. 3 from the tip side in the axial direction. As shown in Figs. 3 and 4, the shaft tip 31 has a radial dust-suction passage 32 that communicates with the axial dust-suction passage 60 and extends in the radial direction, and a dust guide groove 40 provided on the outer circumferential surface of the shaft tip 31.

[0019] The bit shaft portion 30 includes a plurality of (for example, two) radial dust suction passages 32 and a plurality of dust guide grooves 40. The plurality of radial dust suction passages 32 have the same shape and dimensions. The plurality of dust guide grooves 40 also have the same shape and dimensions.

[0020] The bit shaft portion 30 has an end face 31a facing the tip side in the axial direction. The end face 31a has a perfect circular shape when viewed from the tip side in the axial direction. The bit tip portion 10 is joined to the end face 31a so as to partially expose the end face 31a. The bit tip portion 10 has a plurality of (for example, three) ridge-shaped cutting edge portions 11 extending radially outward from the center of the bit tip portion 10 when viewed from the tip side in the axial direction. That is, the plurality of cutting edge portions 11 are connected to each other at the center of the bit tip portion 10 when viewed from the tip side in the axial direction. The ridges between the rake face and the relief face formed on these cutting edge portions 11 are the cutting edges 11a of the bit tip portion 10. The outer diameter of the bit tip portion 10 is larger than the outer diameter of the bit shaft portion 30. As a result, a gap is generated between the inner peripheral surface of the hole of the workpiece P being drilled and the outer peripheral surface of the bit shaft portion 30. The gap is represented by a gap between an imaginary circle C1, which will be described later, and the outer circumferential surface of the bit shaft portion 30.

[0021] Each of the radial dust suction passages 32 has a dust suction port 33 that opens radially outward. Each of the dust suction ports 33 is disposed in a dust guide groove 40. Each of the dust suction ports 33 has a perfect circular shape when viewed from the radial direction, and the flow path cross section of the radial dust suction passage 32 is also perfect circular. Each of the dust suction ports 33 has the same shape and dimensions as each other, and is provided at the same position relative to the corresponding dust guide groove 40. Each of the dust suction ports 33 is separated from the bit tip 10 in the axial direction. The sum of the areas of the dust suction ports 33 is equal to the cross-sectional area of ​​the axial dust suction passage 60, for example.

[0022] The dust guide groove 40 extends in the axial direction. The dust guide groove 40 has an arc shape when viewed from the axial direction. The dust guide groove 40 is disposed in the exposed area of ​​the end surface 31a and has an introduction opening 41 that opens to the tip side in the axial direction. When viewed from the tip side in the axial direction, the introduction opening 41 is away from the bit tip portion 10. When viewed from the tip side in the axial direction, the shortest distance between the introduction opening 41 and the bit tip portion 10 is, for example, longer than the depth dimension d of the dust guide groove 40, and in this embodiment, is longer than twice the depth dimension d of the dust guide groove 40. Furthermore, the shortest distance can be longer than the distance L. The depth dimension d of the dust guide groove 40 at the introduction opening 41 is smaller than the width dimension W of the dust guide groove 40 at the introduction opening 41. The width dimension W is equal to or larger than the diameter D of a virtual circle C2 described later. The width dimension W is, for example, constant in the axial direction from the introduction opening 41 to the dust suction port 33. The depth dimension d of the dust guide groove 40 is also constant, for example, from the introduction opening 41 to the dust suction port 33 in the axial direction.

[0023] The cutting edges 11a each extend radially from the center of the bit tip portion 10 when viewed from the tip side in the axial direction. When viewed from the tip side in the axial direction, the cutting edges 11a each have a straight line shape. When viewed from the tip side in the axial direction, the radial inner ends of the cutting edges 11a each coincide with the center of the bit tip portion 10 and the axis AX of the bit shaft portion 30.

[0024] When viewed from the tip side in the axial direction, a virtual circle C1 (first virtual circle) is defined that is centered on the axis AX of the bit shaft portion 30 and passes through the radial outer end of the cutting blade portion 11. In addition, a virtual circle C2 (second virtual circle) having the maximum area among the virtual circles contained in the dust suction port 33 when viewed from the radial direction is defined. In this embodiment, the dust suction port 33 has a perfect circular shape when viewed from the radial direction. Therefore, the virtual circle C2, which is the maximum diameter among the virtual circles contained in the dust suction port 33 when viewed from the radial direction, completely overlaps with the dust suction port 33 when viewed from the radial direction. In other words, the virtual circle contained in the dust suction port 33 includes a virtual circle that at least a part of which overlaps with the outline of the dust suction port 33 when viewed from the radial direction.

[0025] A distance L between the imaginary circle C1 and the radial inner end of the introduction opening 41 is shorter than a diameter D of the imaginary circle C2. The distance L is also shorter than a width dimension W of the dust guide groove 40 at the introduction opening 41. The width dimension W is larger than the diameter D of the imaginary circle C2.

[0026] According to the above-described configuration, since the distance L is shorter than the diameter D of the virtual circle C2, the dust generated by the cutting blade portion 11 cutting the workpiece P during the drilling operation enters the dust guide groove 40 from the introduction opening 41, passes through the dust guide groove 40, and is sucked into the dust suction port 33. The radial distance L between the virtual circle C1 showing the rotation trajectory of the radial outer end of the cutting blade portion 11 and the radial inner end of the introduction opening 41 is shorter than the diameter D of the virtual circle C2 with the maximum area among the virtual circles contained in the dust suction port 33 when viewed from the radial direction. This makes it difficult for foreign matter that blocks the dust suction port 33 to pass through the introduction opening 41 of the dust guide groove 40. Therefore, it is possible to prevent foreign matter from blocking the dust suction port 33, and to improve the efficiency of the drilling operation while suctioning dust.

[0027] In addition, since the distance L is smaller than the width dimension W of the dust guide groove 40 at the introduction opening 41, foreign matter that may block the dust suction port 33 is unlikely to pass through the introduction opening 41 of the dust guide groove 40, just as in the case where the distance L is shorter than the diameter D of the imaginary circle C2. Therefore, it is possible to prevent foreign matter from blocking the dust suction port 33, and it is possible to increase the efficiency of the drilling work while suctioning dust.

[0028] Furthermore, the depth dimension d of the dust guide groove 40 at the introduction opening 41 is smaller than the width dimension W of the dust guide groove 40 at the introduction opening 41. According to this configuration, the depth dimension d of the dust guide groove 40 at the introduction opening 41 is relatively small, thereby preventing foreign matter from entering the dust guide groove 40, while the width dimension W of the dust guide groove 40 at the introduction opening 41 is relatively large, thereby enabling dust to be widely guided to the dust guide groove 40.

[0029] The bit shaft portion 30 has an end face 31a facing the tip side in the axial direction, the bit tip portion 10 is joined to the end face 31a so as to partially expose the end face 31a, and the introduction opening 41 is disposed in the exposed area of ​​the end face 31a. With this configuration, it is not necessary to machine the bit tip portion 10 for the dust guide groove 40, and manufacturing efficiency can be improved.

[0030] In addition, when viewed from the tip side in the axial direction, the introduction opening 41 is spaced apart from the bit tip portion 10. With this configuration, foreign matter that has reached the introduction opening 41 of the dust guide groove 40 can easily leave the introduction opening 41, and the foreign matter can be crushed by the bit tip portion 10.

[0031] Moreover, the dust guide groove 40 has an arc shape when viewed from the axial direction. With this configuration, the dust guide groove 40 can be easily formed by simple groove processing.

[0032] Moreover, the sum of the areas of the multiple dust suction ports 33 is equal to the cross-sectional area of ​​the axial dust suction passage 60. With this configuration, dust can be guided from the dust suction port 33 to the axial dust suction passage 60 without excess or deficiency. If the sum of the areas of the multiple dust suction ports 33 is larger than the cross-sectional area of ​​the axial dust suction passage 60, the amount of dust sucked in from the dust suction port 33 becomes too large, and dust may clog in the axial dust suction passage 60. On the other hand, if the sum of the areas of the multiple dust suction ports 33 is smaller than the cross-sectional area of ​​the axial dust suction passage 60, the amount of dust sucked in from the dust suction port 33 becomes small, and the dust suction efficiency may deteriorate.

[0033] Moreover, the dust suction port 33 is separated from the bit tip portion 10 in the axial direction. According to this configuration, the dust suction port 33 is formed avoiding the portion of the bit shaft portion 30 close to the bit tip portion 10 where a relatively large load is applied, thereby improving durability.

[0034] Moreover, the dust guide groove 40 extends in the axial direction. According to this configuration, the dust guide groove 40 can be easily formed by groove machining the outer peripheral surface of the bit shaft portion 30 in the axial direction.

[0035] Moreover, the width dimension W of the dust guide groove 40 is equal to or larger than the diameter D of the imaginary circle C2. With this configuration, dust can be sufficiently guided to the dust suction port 33 through the dust guide groove 40. In this embodiment, the width dimension W is larger than the diameter D of the imaginary circle C2. With this configuration, the imaginary circle C2 can be easily disposed inside the dust guide groove 40 when viewed from the radial direction. Therefore, for example, the manufacturing yield of the dust suction drill bit can be improved compared to the case where the width dimension W of the dust guide groove 40 is the same as the diameter D of the imaginary circle C2.

[0036] Moreover, the radial dust suction passage 32 has a flow path cross section in a perfect circular shape. According to this configuration, the radial dust suction passage 32 can be easily formed by simple hole processing.

[0037] Fig. 5 is a view of a part of the dust-suction drill bit 1B according to the first modified example, showing the dust-suction port 33 and its surrounding area from the radial direction. The dust-suction drill bit 1B has a structure similar to that of the dust-suction drill bit 1A, except for the joining mode of the bit tip portion 10 and the bit shaft portion 30, the dust-suction port 33, and the dust guide groove 40. Therefore, the same or similar parts are given the same reference numerals, and similar descriptions will not be repeated. Also, in Fig. 5, the tip side of the bit tip portion 10 where the cutting blade portion 11 is located is omitted.

[0038] As shown in Fig. 5, in the dust-vacuum drill bit 1B, the bit tip portion 10 is engaged with the bit shaft portion 30 in the axial direction. The bit shaft portion 30 of the dust-vacuum drill bit 1B has a tip recess 35 at its tip portion. A radial groove that opens to the tip side of the bit shaft portion 30 and extends in the radial direction is formed in the tip recess 35 of the bit shaft portion 30. The bit tip portion 10 of the dust-vacuum drill bit 1B has a base end protrusion 15 at its base end portion. The tip recess 35 has a shape that corresponds to the base end protrusion 15.

[0039] The bit tip 10 is joined to the bit shaft 30 with the base end protrusion 15 of the bit tip 10 fitted into the tip recess 35 of the bit shaft 30. The radial dust suction passage 32 is formed by covering the radial groove formed in the tip recess 35 of the bit shaft 30 from the axial tip side with the flat bottom surface of the bit tip 10. Therefore, the dust suction port 33 of the radial dust suction passage 32 has a U-shape and is a non-circular shape. In this case, the virtual circle C2 with the maximum area among the virtual circles contained in the dust suction port 33 when viewed from the radial direction is inscribed in the straight line portion of the contour of the U-shaped dust suction port 33.

[0040] The dust-vacuum drill bit 1B has a dust guide groove 40 extending in the axial direction on its outer circumferential surface. The dust guide groove 40 is provided continuously on the bit shaft portion 30 and the bit tip portion 10. That is, the bit tip portion 10 covers most of the radial groove from the axial direction while exposing the radially outer end of the radial groove in the axial direction. The bit tip portion 10 has an introduction opening that opens to the axial tip side of the dust guide groove 40.

[0041] Even with the dust-vacuuming drill bit 1B having the above-described dust-vacuuming port 33 and dust guide groove 40, it is possible to obtain the same effects as those of the dust-vacuuming drill bit 1A.

[0042] Fig. 6A is a perspective view of a part of a dust-vacuum drill bit 1C according to a second modified example, showing the bit tip 10 and its surrounding area. Fig. 6B is a view of the dust-vacuum drill bit 1C of Fig. 6A as seen from the axial tip side. The dust-vacuum drill bit 1C has a similar structure to the dust-vacuum drill bit 1A, except for the axial tip portion of the bit shaft portion 30 and the bit tip 10. Therefore, the same or similar parts are given the same reference numerals, and similar descriptions will not be repeated.

[0043] 6A and 6B, the bit tip portion 10 of the dust-suction drill bit 1C has a tip main portion 20 and a plurality of (for example, two) tip sub-portions 25 that are smaller than the tip main portion 20. The tip main portion 20 and the plurality of tip sub-portions 25 each have a cutting edge portion 11. When viewed from the tip side in the axial direction, the tip main portion 20 and the plurality of tip sub-portions 25 are each joined to the bit shaft portion 30 so as to partially expose the end face 31a and the axial dust-suction passage 60, respectively.

[0044] The tip main portion 20 has a first main portion 21 extending radially along an end face 31a facing the axial tip side of the bit shaft portion 30 and including a cutting edge portion 11, a second main portion 22 extending from one radial outer end of the first main portion 21 to the base end side in the axial direction along the outer peripheral surface of the bit shaft portion 30, and a third main portion 23 extending from the other radial outer end of the first main portion 21 to the base end side in the axial direction along the outer peripheral surface of the bit shaft portion 30.

[0045] The first main portion 21 has a rectangular shape extending radially through the axis AX of the bit shaft portion 30 as viewed from the tip side in the axial direction. The two radial outer ends of the first main portion 21 are located outside the outer circumferential surface of the bit shaft portion 30 as viewed from the tip side in the axial direction. The cutting edge 11a of the cutting edge portion 11 of the first main portion 21 passes through the center of the bit tip portion 10 and the axis AX of the bit shaft portion 30 as viewed from the tip side in the axial direction and extends linearly in the radial direction. The first main portion 21 has a protruding portion 21a having a shape like the tip of a quadrangular pyramid protruding toward the tip side in the axial direction at a portion overlapping with the axial dust suction passage 60 as viewed from the tip side in the axial direction. The ridge extending linearly from the apex of the protruding portion 21a is the radial center portion of the cutting edge 11a of the cutting edge portion 11 of the first main portion 21. Furthermore, the first main portion 21 has a base end portion 21b extending toward the base end side in the axial direction at a portion overlapping with the axial dust suction passage 60 when viewed from the tip side in the axial direction. The base end portion 21b extends within the axial dust suction passage 60 in the axial direction.

[0046] Each of the multiple tip sub-portions 25 has a first sub-portion 26 extending radially along an end face 31a facing the axial tip side of the bit shaft portion 30 and including a cutting edge 11a of the cutting edge portion 11, a second sub-portion 27 extending from the radial outer end of the first sub-portion 26 toward the axial base end side along the outer circumferential surface of the bit shaft portion 30, and a third sub-portion 28 extending from the radial inner end of the first sub-portion 26 toward the axial base end side within the axial dust suction passage 60.

[0047] Each of the first sub-portions 26 is substantially rectangular and extends radially when viewed from the tip side in the axial direction. The radial outer ends of the first sub-portions 26 are located outside the outer circumferential surface of the bit shaft portion 30 when viewed from the tip side in the axial direction. The radial inner ends of the first sub-portions 26 are located in the axial dust suction passage 60 when viewed from the tip side in the axial direction, and are adjacent to the first main portion 21 on the radial outer side. The cutting edges 11a of the cutting edge portions 11 of the first sub-portions 26 each extend linearly in the radial direction when viewed from the tip side in the axial direction. Each of the first sub-portions 26 has a protruding portion 26a that protrudes from the radial center portion to the tip side in the axial direction and has a shape like the tip portion of a quadrangular pyramid. The ridge extending linearly from the apex of the protruding portion 26a is the radial center portion of the cutting edge 11a of the cutting edge portion 11 of the first sub-portion 26. In this modified example, the dust-vacuum drill bit 1C has two tip sub-portions 25. When viewed from the tip side in the axial direction, a straight line connecting the cutting edge 11a of the cutting portion 11 of one tip sub-portion 25 and the cutting edge 11a of the cutting portion 11 of the other tip sub-portion 25 passes through the axis AX of the bit shaft portion 30.

[0048] The dust-vacuum drill bit 1C equipped with the bit tip 10 as described above can achieve the same effect as the dust-vacuum drill bit 1A, since the bit shaft portion 30 has the radial dust-vacuum passage 32 and the dust guide groove 40. Furthermore, the dust-vacuum drill bit 1C has a bit tip 10 equipped with multiple (e.g., two) tip sub-portions 25, so that the bit tip 10 can perform drilling work on the workpiece P with high accuracy.

[0049] 7 is a view of a dust-vacuum drill bit 1D according to a third modified example, viewed from the tip side in the axial direction. The dust-vacuum drill bit 1D has a structure similar to that of the dust-vacuum drill bit 1A, except for the bit tip portion 10. Therefore, the same or similar parts are given the same reference numerals, and similar descriptions will not be repeated.

[0050] As shown in FIG. 7, the bit tip 10 of the dust-vacuum drill bit 1D is joined to the bit shaft 30 so that an end face 31a facing the axial tip of the bit shaft 30 is partially exposed when viewed from the axial tip. The bit tip 10 of the dust-vacuum drill bit 1D has a plurality of cutting blade portions 11. The cutting blades 11a of the plurality of cutting blade portions 11 each extend radially from the center of the bit tip 10 when viewed from the axial tip. Each of the plurality of cutting blades 11a has a first straight portion extending radially from the center of the bit tip 10 when viewed from the axial tip, and a second straight portion extending radially from the outer end of the first straight portion and bending with respect to the first straight portion.

[0051] Even with the dust-vacuum drill bit 1D having the bit tip portion 10 as described above, since the bit shaft portion 30 has the radial dust-vacuum passage 32 and the dust guide groove 40, it is possible to obtain the same effects as the dust-vacuum drill bit 1A.

[0052] 8 is a view of the dust-vacuuming drill bit 1E according to the fourth modified example, viewed from the tip side in the axial direction. The dust-vacuuming drill bit 1D has a structure similar to that of the dust-vacuuming drill bit 1A, except for the dimensions of the axial dust-vacuuming passage 60 and the bit tip portion 10. Therefore, the same or similar parts are given the same reference numerals, and similar descriptions will not be repeated.

[0053] 8, the bit tip portion 10 of the dust-suction drill bit 1E is joined to the bit shaft portion 30 so as to partially expose the end face 31a and the axial dust-suction passage 60 when viewed from the tip side in the axial direction. The diameter of the axial dust-suction passage 60 of the dust-suction drill bit 1E is larger than that of the dust-suction drill bit 1A.

[0054] The bit tip 10 of the dust-vacuum drill bit 1E has a rectangular shape extending radially through the axis AX of the bit shaft 30 when viewed from the tip side in the axial direction. The bit tip 10 has two cutting blade portions 11. When viewed from the tip side in the axial direction, the cutting blades 11a of the two cutting blade portions 11 extend linearly in the extension direction of the bit tip 10 and have a pair of ridge lines that have radially inner ends at a position shifted from the center of the bit tip 10 in a direction perpendicular to the extension direction of the bit tip 10, and a ridge line that connects the radially inner ends of the pair of ridge lines and passes through the center of the bit tip 10.

[0055] Even with the dust-vacuum drill bit 1E having the bit tip portion 10 as described above, since the bit shaft portion 30 has the radial dust-vacuum passage 32 and the dust guide groove 40, it is possible to obtain the same effects as the dust-vacuum drill bit 1A.

[0056] The technology of the present disclosure is not limited to the above-mentioned configuration. For example, in the above embodiment, the width dimension W of the dust guide groove 40 and the depth dimension d of the dust guide groove 40 are constant in the axial direction from the introduction opening 41 to the dust suction port 33. However, this is not limited to this case, and for example, the width dimension W may become smaller from the introduction opening 41 toward the dust suction port 33. Also, for example, the depth dimension d may become larger from the introduction opening 41 toward the dust suction port 33.

[0057] In the above embodiment, the dust guide groove 40 is described as having an arc shape when viewed from the axial direction. However, the present invention is not limited to this case, and the dust guide groove 40 may have a shape that connects one point on the outer edge of the bit shaft portion 30 to another point on the outer edge in a straight line when viewed from the axial direction.

[0058] In the above embodiment, the dust guide groove 40 extends linearly in the axial direction. However, the present invention is not limited to this, and the dust guide groove 40 may extend linearly in a direction mainly composed of the axial direction. For example, the dust guide groove 40 may be inclined with respect to the axial direction, or may extend in the axial direction while being curved. Moreover, the dust guide groove 40 does not have to extend linearly, and may have a portion extending in the circumferential direction in addition to a portion extending in the axial direction.

[0059] In the above embodiment, the case where the multiple radial dust suction passages 32 have the same shape and the same dimensions, and the multiple dust guide grooves 40 also have the same shape and the same dimensions, has been described. However, this is not limited to this case, and for example, the multiple radial dust suction passages 32 may have different shapes and different dimensions, and the multiple dust guide grooves 40 may also have different shapes and different dimensions.

[0060] In the above embodiment, the multiple dust suction ports 33 have the same shape and dimensions, and are provided at the same positions relative to the corresponding dust guide grooves 40. However, this is not limited to the above case. For example, the multiple dust suction ports 33 may have different shapes and dimensions, and be provided at different positions relative to the corresponding dust guide grooves 40.

[0061] In the above embodiment, the case where the dust suction port 33 is a perfect circle when viewed from the radial direction has been described. Also, in the above first modified example, the case where the dust suction port 33 is a U-shape when viewed from the radial direction as shown in FIG. 5 has been described. However, the present invention is not limited to these cases, and the dust suction port 33 may be, for example, a semicircular shape or an elliptical shape when viewed from the radial direction. Note that the radial dust suction passage 32 may be an elliptical shape when viewed from the radial direction by having a flow path cross section of a perfect circle and being inclined with respect to the radial direction when viewed from the axial direction.

[0062] In the above embodiment, the case where the sum of the areas of the multiple dust suction ports 33 is equal to the cross-sectional area of ​​the axial dust suction passage 60 has been described. However, this is not limited to this case, and the sum of the areas of the multiple dust suction ports 33 may be larger or smaller than the cross-sectional area of ​​the axial dust suction passage 60.

[0063] In the above embodiment, the radial dust suction passage 32 has a flow passage cross section in a perfect circular shape. However, the present invention is not limited to this case, and the radial dust suction passage 32 may have a flow passage cross section in an elliptical shape, for example.

[0064] In the above embodiment, the bit shaft portion 30 includes two radial dust suction passages 32 and two dust guide grooves 40. However, this is not limited to the above, and the number of radial dust suction passages 32 and dust guide grooves 40 in the bit shaft portion 30 may be one, or three or more.

[0065] In the above embodiment, the bit tip portion 10 and the bit shaft portion 30 are joined to each other. However, the present invention is not limited to this, and the bit tip portion 10 and the bit shaft portion 30 may be integrally formed from metal.

[0066] In the above embodiment, the bit tip portion 10 has three cutting edges 11. However, the present invention is not limited to this, and the number of cutting edges 11 may be one, two, or four or more. Preferably, the number of cutting edges 11 is four or less. More preferably, the number of cutting edges 11 is three or less.

[0067] As described above, the above embodiment has been described as an example of the technology disclosed in this application. However, the technology in this disclosure is not limited to this, and can be applied to embodiments in which modifications, replacements, additions, omissions, etc. have been made as appropriate. In addition, it is also possible to combine the components described in the above embodiment to create a new embodiment. For example, a part of the configuration or method in one embodiment may be applied to another embodiment, and a part of the configuration in an embodiment can be separated from other configurations in that embodiment and arbitrarily extracted. In addition, the components described in the attached drawings and detailed description include not only components essential for solving the problem, but also components that are not essential for solving the problem in order to exemplify the technology.

[0068] Each of the following sections is a disclosure of a preferred embodiment.

[0069] [Item 1] A drill bit comprising: a bit shaft portion; and a bit tip portion provided on a tip side of the bit shaft portion in an axial direction and having a cutting edge portion, The bit shaft portion is An axial dust suction passage extending in the axial direction; A radial dust suction passage communicating with the axial dust suction passage and having a dust suction port opening radially outwardly in a direction perpendicular to the axial direction; A dust guide groove is provided on the outer peripheral surface of the bit shaft portion and has the dust suction port arranged therein, the dust guide groove having an introduction opening that opens to the tip side in the axial direction, A dust-suction drill bit, wherein the radial distance between a first imaginary circle centered on the axis of the bit shaft portion and passing through the radial outer end of the cutting blade portion when viewed from the tip side in the axial direction, and the radial inner end of the introduction opening, is shorter than the diameter of a second imaginary circle having the largest area among the imaginary circles contained within the dust suction port when viewed from the radial direction. [Item 2] A drill bit comprising: a bit shaft portion; and a bit tip portion provided on a tip side of the bit shaft portion in an axial direction and having a cutting edge portion, The bit shaft portion is An axial dust suction passage extending in the axial direction; A radial dust suction passage communicating with the axial dust suction passage and having a dust suction port opening radially outwardly in a direction perpendicular to the axial direction; A dust guide groove is provided on the outer peripheral surface of the bit shaft portion and has the dust suction port arranged therein, the dust guide groove having an introduction opening that opens to the tip side in the axial direction, a dust-collecting drill bit, wherein when viewed from the tip side in the axial direction, the radial distance between a first virtual circle centered on the axis of the bit shaft portion and passing through the radial outer end of the cutting blade portion and the radial inner end of the introduction opening is smaller than a width dimension of the dust guide groove at the introduction opening. [Item 3] 3. The dust-vacuum drill bit according to item 1 or 2, wherein a depth dimension of the dust guide groove at the inlet opening is smaller than a width dimension of the dust guide groove at the inlet opening. [Item 4] The bit shaft portion has an end surface facing the tip side in the axial direction, the bit tip portion is joined to the end surface of the bit shaft portion so as to partially expose the end surface of the bit shaft portion, 4. The dust-vacuuming drill bit according to any one of items 1 to 3, wherein the inlet opening is disposed in an exposed area of ​​the end face of the bit shaft portion. [Item 5] 5. The dust-vacuum drill bit according to item 4, wherein the introduction opening is spaced apart from the bit tip when viewed from the tip side in the axial direction. [Item 6] 6. The dust-vacuum drill bit according to any one of items 1 to 5, wherein the dust guide groove has an arc shape when viewed from the axial direction. [Item 7] The bit shaft portion includes a plurality of radial dust suction passages and a plurality of dust guide grooves, 7. The dust suction drill bit according to any one of items 1 to 6, wherein the sum of the areas of the plurality of dust suction ports is equal to the cross-sectional area of ​​the axial dust suction passage. [Item 8] 8. The dust-suction drill bit according to claim 1, wherein the dust-suction port is spaced apart from the bit tip in the axial direction. [Item 9] 9. The dust-vacuuming drill bit according to claim 1, wherein the dust guide groove extends in the axial direction. [Item 10] 10. The dust-suction drill bit according to claim 1, wherein a width dimension of the dust guide groove is equal to or larger than a diameter of the second imaginary circle of the dust suction port. [Item 11] 11. The dust suction drill bit according to claim 1, wherein a flow path cross section of the radial dust suction passage has a perfect circular shape. [Explanation of symbols]

[0070] 1A to 1E Dust extraction drill bit 10 Bit tip 11 Cutting edge 30 Bit shaft section 31a End face 32 Radial dust collection passage 33 Dust intake port 40 Dust guide groove 41 Introduction opening 60 Axial dust collection passage AX axis C1 Virtual circle (first virtual circle) C2 Virtual circle (second virtual circle) D diameter (diameter of the second imaginary circle) L distance d Depth dimension W Width dimension

Claims

1. A drill bit comprising: a bit shaft portion; and a bit tip portion provided on a tip side of the bit shaft portion in an axial direction and having a cutting edge portion, The bit shaft portion is An axial dust suction passage extending in the axial direction; A radial dust suction passage communicating with the axial dust suction passage and having a dust suction port opening radially outwardly in a direction perpendicular to the axial direction; A dust guide groove is provided on the outer peripheral surface of the bit shaft portion and has the dust suction port disposed therein, the dust guide groove having an introduction opening that opens to the tip side in the axial direction, A dust-suction drill bit, wherein when viewed from the tip side in the axial direction, the radial distance between a first virtual circle centered on the axis of the bit shaft portion and passing through the radial outer end of the cutting blade portion, and the radial inner end of the introduction opening, is shorter than the diameter of a second virtual circle having the largest area among the virtual circles contained in the dust suction port when viewed from the radial direction.

2. A drill bit comprising: a bit shaft portion; and a bit tip portion provided on a tip side of the bit shaft portion in an axial direction and having a cutting edge portion, The bit shaft portion is An axial dust suction passage extending in the axial direction; A radial dust suction passage communicating with the axial dust suction passage and having a dust suction port opening radially outwardly in a direction perpendicular to the axial direction; A dust guide groove is provided on the outer peripheral surface of the bit shaft portion and has the dust suction port disposed therein, the dust guide groove having an introduction opening that opens to the tip side in the axial direction, a dust-collecting drill bit, wherein when viewed from the tip side in the axial direction, the radial distance between a first virtual circle centered on the axis of the bit shaft portion and passing through the radial outer end of the cutting blade portion and the radial inner end of the introduction opening is smaller than a width dimension of the dust guide groove at the introduction opening.

3. The dust-vacuuming drill bit according to claim 1 or 2, wherein a depth dimension of the dust guide groove at the inlet opening is smaller than a width dimension of the dust guide groove at the inlet opening.

4. The bit shaft portion has an end surface facing the tip side in the axial direction, the bit tip portion is joined to the end surface of the bit shaft portion so as to partially expose the end surface of the bit shaft portion, The dust-vacuuming drill bit according to claim 1 or 2, wherein the inlet opening is disposed in an exposed area of ​​the end face of the bit shaft portion.

5. The dust-vacuum drill bit according to claim 4 , wherein the introduction opening is spaced apart from the bit tip when viewed from the tip side in the axial direction.

6. The dust-vacuuming drill bit according to claim 1 or 2, wherein the dust guide groove has an arc shape when viewed from the axial direction.

7. The bit shaft portion includes a plurality of radial dust suction passages and a plurality of dust guide grooves, The dust suction drill bit according to claim 1 or 2, wherein a sum of the areas of the plurality of dust suction ports is equal to a cross-sectional area of ​​the axial dust suction passage.

8. The dust-suction drill bit according to claim 1 or 2, wherein the dust-suction port is spaced apart from the bit tip in the axial direction.

9. The dust-vacuuming drill bit according to claim 1 or 2, wherein the dust guide groove extends in the axial direction.

10. The dust-suction drill bit according to claim 1 or 2, wherein a width dimension of the dust guide groove is equal to or larger than a diameter of the second imaginary circle of the dust suction port.

11. The dust suction drill bit according to claim 1 or 2, wherein a flow passage cross section of the radial dust suction passage has a perfect circular shape.

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