Drill bit

Abstract

To provide a drill bit attached to a drill shank and used.SOLUTION: A drill bit 1 includes a drill bit shaft 4, a plurality of blades 6a, 6b provided at the tip of the shaft 4, a groove 2 for receiving drilling powder provided between the blades 6a, 6b, and a dust suction hole 3 provided in each of the groove 2 for receiving drilling powder to be connected to a dust suction passage provided inside the shaft 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drill bit. [Background technology]

[0002] The following drill bit is known: In this drill bit, which includes a bit shaft portion and a bit tip portion radially arranged so that cutting blade portions extend radially outward, the bit shaft portion is provided with a dust suction passage extending in the longitudinal direction with its tip end extending to the tip surface of the bit shaft portion and its base end communicating with a suction device, the center point of the suction port of the dust suction passage formed in the tip surface of the bit shaft portion is eccentric with respect to the center point of the tip surface of the bit shaft portion, and the suction port is open in a portion of the tip surface of the bit shaft portion that is not covered by the bit tip portion (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-112732 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, in rooftop waterproofing work (including renovation work) on buildings, a concrete drill capable of drilling holes while suctioning dust is used when drilling holes in a concrete structure including insulation. In this way, a concrete drill capable of drilling holes while suctioning dust is used with a drill bit having a dust suction hole at the tip, and dust such as cutting chips is sucked and removed from the dust suction hole provided at the tip of the drill bit. In this way, when dust is sucked from the dust suction hole provided at the tip of the drill bit, there is a problem that the insulation material or the waterproof material softened by heat clogs the dust suction hole, or the insulation material or waterproof material sucked from the dust suction hole clogs the dust suction passage. For this reason, a technology to solve such problems is required, but no technology for this purpose has been considered in the past. [Means for solving the problem]

[0005] The drill bit according to the present invention is characterized in that it comprises a drill bit shaft, a plurality of blades provided at the tip of the shaft, drilling powder receiving grooves provided between the blades, and dust suction holes provided in each of the drilling powder receiving grooves so as to connect to dust suction passages provided inside the shaft. Effect of the Invention

[0006] According to the present invention, the dust suction hole is provided in the drilling powder receiving groove, so that the inner surface of the hole opened by drilling does not come into contact with the dust suction hole during drilling, and the dust suction hole can be prevented from being directly blocked. In addition, the drilling powder receiving grooves machined in multiple places on the shaft do not wrap around and adhere to the insulation material generated by the drilling work or the waterproof material softened by heat, so the dust suction hole can be prevented from being blocked. Furthermore, the insulation material, waterproof material, etc. are not sucked in through the dust suction hole, so the dust suction passage can be prevented from being blocked. [Brief description of the drawings]

[0007] [Figure 1] 1A to 1C are diagrams showing the shape of a drill bit 1 in a first embodiment. [Diagram 2]2 is a diagram showing a schematic diagram of a dust collection passage provided inside the shaft of the drill bit 1 in the first embodiment. FIG. [Diagram 3] FIG. 1 is a schematic cross-sectional view of a drill bit 1 according to a first embodiment. [Figure 4] FIG. 1 is a diagram showing a concrete drill shank 10 with a dust collection function to which a drill bit 1 in the first embodiment is connected, and a schematic diagram showing an example of a connection between the drill bit 1 and the concrete drill shank 10 with a dust collection function. [Diagram 5] FIG. 2 is a diagram showing a schematic diagram of a dust suction passage provided inside a drill bit 1 and a concrete drill shank 10 with a dust suction function in the first embodiment. [Figure 6] 6A to 6C are diagrams showing the shape of a drill bit 1 according to a second embodiment. [Figure 7] 13 is a diagram showing a schematic diagram of a dust collection passage provided inside the shaft of a drill bit 1 in a second embodiment. FIG. [Figure 8] FIG. 11 is a schematic cross-sectional view of a drill bit 1 according to a second embodiment. [Figure 9] 13 is a diagram showing a concrete drill shank 10 with a dust collection function to which a drill bit 1 in a second embodiment is connected, and a schematic diagram showing an example of connection between the drill bit 1 and the concrete drill shank 10 with a dust collection function. FIG. [Figure 10] FIG. 11 is a diagram showing a schematic diagram of a dust suction passage provided inside a drill bit 1 and a concrete drill shank 10 with a dust suction function in a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] --First embodiment-- In waterproofing renovation work on the roofs of buildings, there is a method of covering the existing waterproofing with asphalt waterproofing material. In the past, materials containing asphalt were used as asphalt waterproofing materials, so when drilling into this material in the covering method, it is an issue to prevent asbestos from scattering. It cannot be denied that the drilling powder generated during drilling work may be mixed with the drilling powder of this asphalt waterproofing material.

[0009] The drill bit in the first embodiment is connected to a drill shank and attached to an electric rotating device for use, and is assumed to be, for example, a drill bit attached to a concrete drill shank with a dust suction function. In order to solve the above problems, this drill bit is provided with a dust suction hole for suctioning dust such as drilling powder and cutting chips during drilling work such as rooftop waterproofing work (including renovation work), and is configured to prevent the dust suction hole from being clogged with insulation material, waterproofing material, etc. The drill bit in this embodiment will be described below.

[0010] Fig. 1 is a diagram showing the shape of a drill bit 1 in the first embodiment. Fig. 1 shows a two-blade type drill bit 1 having two blades at the tip of the drill bit. In Fig. 1, the right side of the figure is a connection part that is connected to a concrete drill shank with a dust collection function, and the left side of the figure is a drill tip part equipped with the blades.

[0011] As shown in Fig. 1(A), the drill bit 1 in this embodiment is provided with two blades 6a and 6b at the tip of the drill bit. When the drill bit 1 is connected to a drill and the shaft 4 rotates, the blades 6a and 6b rotate together with the shaft 4 to perform drilling work. The shaft 4 is provided with a drilling powder receiving groove 2 between the blades 6a and 6b at the tip of the drill, and a dust collection hole 3 is provided in the drilling powder receiving groove 2. The tip of the drill bit 1 is provided with a carbide tip 5.

[0012] In the drill bit 1 of this embodiment, a rod-shaped shaft 4 of the drill bit 1 has a section that is one step thinner between the tip side and the connection side. In the example shown in Fig. 1(A), the thickness of the shaft 4 in the middle part between the tip side 4a and the connection side 4b is thinner than the thickness of the shaft to the left of 4a and the thickness of the shaft to the right of 4b.

[0013] Fig. 1(B) is a view of the drill bit 1 shown in Fig. 1(A) from the opposite side. That is, Fig. 1(B) shows the drill bit 1 shown in Fig. 1(A) rotated 180 degrees around the shaft 4 as the axis of rotation. Therefore, in Fig. 1(B), the blade 6a, which was located on the upper side in Fig. 1(A), is located on the lower side, and the blade 6b, which was located on the lower side in Fig. 1(A), is located on the upper side.

[0014] In Fig. 1(B), as in Fig. 1(A), a drilling powder receiving groove 2 is provided between the blades 6a and 6b at the tip of the drill, and a dust collection hole 3 is provided in the drilling powder receiving groove 2. A carbide tip 5 is provided at the tip of the drill bit 1. The rod-shaped shaft 4 of the drill bit 1 is configured to be tapered between the tip side and the connection side. In the example shown in Fig. 1(B), the thickness of the shaft 4 in the section between the tip side 4a and the connection side 4b is thinner than the thickness of the shaft to the left of 4a and the thickness of the shaft to the right of 4b.

[0015] In the drill bit 1 of this embodiment, the axial positions of the dust suction holes 3 provided in the drilling powder receiving groove 2 are different. As an example, in FIG. 1(A), one dust suction hole 3 is provided near the center of the drilling powder receiving groove 2, while in the opposite side of FIG. 1(B), one dust suction hole 3 is provided near the tip of the drilling powder receiving groove 2. Thus, in the example shown in FIG. 1, the dust suction holes 3 provided in each drilling powder receiving groove 2 are arranged at different cross-sectional positions. When the diameter of the drill bit 1 is small, if the dust suction holes 3 are machined at the same cross-sectional position, it is susceptible to the influence of strength reduction due to cross-sectional loss. Therefore, in the drill bit 1 of this embodiment, the position of the dust suction hole 3 is shifted in the axial direction, i.e., the longitudinal direction of the shaft 4, to reduce the influence of strength reduction.

[0016] As shown in FIG. 1, in the drill bit 1 of this embodiment, the rod-shaped shaft 4 of the drill bit 1 has a section that is one step thinner between the tip side and the connection side, that is, the section between 4a and 4b in FIG. 1(A) and FIG. 1(B). In this way, by providing a step in the rod-shaped shaft and making a part of the shaft 4 one step thinner, it is possible to prevent the air flowing into the hole from being blocked even if the asphalt waterproofing material wrapped around and attached to the shaft 4 reaches a certain thickness. As a result, even if the waterproofing material softens and becomes viscous due to frictional heat generated during the drilling operation and adheres to the shaft 4, the one-step thinner part of the shaft 4 serves as a step for ventilation, preventing the inflow of air necessary for dust collection from being blocked, and drilling work can be performed continuously without preventing the intake of air into the hole. In addition, even if there is waterproofing material that has already been softened and become viscous due to direct sunlight on the roof of a building and adheres to the shaft 4, it is possible to prevent the inflow of air necessary for dust collection from being blocked.

[0017] In the drill bit 1 of this embodiment, a dust suction passage is provided inside the shaft 4 as a passage for the drilling powder, cuttings, etc., in order to suck up dust and the like such as drilling powder and cuttings through the dust suction hole 3. Figure 2 is a diagram showing the internal structure of the shaft 4 in the drill bit 1 shown in Figure 1 (A) by a broken line. As shown in Figure 2, a dust suction passage 7 is provided inside the shaft 4 so as to penetrate the inside of the shaft 4 in order to suck up the drilling powder, cuttings, etc. sucked in through the dust suction hole 3 toward the connection part of the drill bit 1.

[0018] Figure 3 is a cross-sectional view of the drill bit 1 shown in Figures 1(A) and 1(B) when cut perpendicularly to the axis 4 at the position of the dust suction hole 3. Figure 3(A) shows a cross-sectional view of the drill bit 1 shown in Figure 1(A) when cut perpendicularly to the axis 4 at the position of the dust suction hole 3, and Figure 3(B) shows a cross-sectional view of the drill bit 1 shown in Figure 1(B) when cut perpendicularly to the axis 4 at the position of the dust suction hole 3.

[0019] As shown in Figures 3(A) and 3(B), the shaft 4 is provided with a drilling powder receiving groove 2 between two blades 6a and 6b, and a dust suction hole 3 opens into each drilling powder receiving groove 2. This dust suction hole 3 is provided in a direction perpendicular to the axis and is connected to a dust suction passage 7 provided inside the shaft 4. Also, as shown in Figures 3(A) and 3(B), in this embodiment, the drilling powder receiving groove 2 has a curved shape.

[0020] In this way, in the drill bit 1 of this embodiment, the dust suction hole 3 is provided in the drilling powder receiving groove 2, so that the inner surface of the hole opened by drilling does not come into contact with the dust suction hole 3, and the dust suction hole 3 is not directly blocked. In addition, since insulation material and the like is not sucked in through the dust suction hole 3, it is possible to prevent the dust suction hole 3 and the dust suction passage 7 connected thereto from being blocked.

[0021] Fig. 4(A) is a schematic diagram showing a concrete drill shank 10 with a dust-suction function to which a drill bit 1 in the first embodiment is connected. As shown in Fig. 4(A), the concrete drill shank 10 with a dust-suction function has a connection part 11 for connecting the drill bit 1. In this embodiment, as shown in Fig. 4(B), the drill bit 1 can be connected to the concrete drill shank 10 with a dust-suction function by connecting the connection part 11 of the concrete drill shank 10 with a dust-suction function to the connection part 9 of the drill bit 1.

[0022] As shown by the dashed line in Fig. 5(A), the inside of the concrete drill shank 10 with the dust suction function is provided with a dust suction passage 12 for sucking up the above-mentioned drilling powder, cutting chips, etc. As shown in Fig. 5(B), when the drill bit 1 is connected to the concrete drill shank 10 with the dust suction function, the dust suction passage 7 of the drill bit 1 and the dust suction passage 12 of the concrete drill shank 10 with the dust suction function are connected inside. This allows the drilling powder, cutting chips, etc. sucked in through the dust suction hole 3 to be sucked in using the concrete drill shank 10 with the dust suction function. In Fig. 5, the dust suction passage provided inside is shown by the dashed line.

[0023] According to the first embodiment described above, the following advantageous effects can be obtained. (1) The drill bit 1 comprises a shaft 4 of the drill bit, a plurality of blades 6a and 6b provided at the tip of the shaft 4, a drilling powder receiving groove 2 provided between the blades, and a dust suction hole 3 provided in each drilling powder receiving groove 2 so as to connect to a dust suction passage 7 provided inside the shaft 4. Since the dust suction hole 3 is provided in the drilling powder receiving groove 2 in this way, the inner surface of the hole opened by drilling does not come into contact with the dust suction hole 3, and the dust suction hole 3 can be prevented from being directly blocked. In addition, the asphalt waterproofing material melted by the frictional heat caused by the drilling work does not wrap around and adhere to the drilling powder receiving grooves 2 processed in two places on the shaft 4, so that the dust suction hole 3 can be prevented from being blocked. Furthermore, since insulation material, waterproofing material, etc. are not sucked in through the dust suction hole 3, the dust suction passage 7 can be prevented from being blocked. In addition, the drilling powder of the asphalt waterproofing material wraps around and adheres to the rod-shaped shaft 4, preventing it from scattering. In addition, since the drilling work is performed while dust is being sucked through the dust suction hole 3, it is possible to prevent the drilling powder of concrete, etc. from scattering.

[0024] (2) The drill bit 1 has a step for ventilation created by narrowing the middle part of the shaft 4. This prevents the waterproofing material generated during the drilling operation and the viscous waterproofing material that softens due to frictional heat from the drill and wraps around and adheres to the shaft 4 from blocking the inflow of air needed for dust collection. In this way, by narrowing the rod-shaped shaft in one step, the asphalt waterproofing material that wraps around and adheres to the shaft does not block the air flowing into the hole even when it reaches a certain thickness, so drilling can be performed continuously without interfering with the intake of air into the hole.

[0025] (3) The dust suction holes 3 are arranged at different axial positions. As a result, if the drill bit has a small diameter and the dust suction holes 3 are machined at the same cross-sectional position, the strength is likely to be reduced due to cross-sectional loss. However, by displacing the positions of the dust suction holes 3 in the axial direction, i.e., the longitudinal direction of the shaft 4, as in the drill bit 1 of this embodiment, the influence of the reduction in strength can be reduced.

[0026] --Second embodiment-- In the above-mentioned first embodiment, a two-blade type drill bit having two blades at the tip of the drill bit has been described. The present invention is not limited to two blades at the tip of the drill bit, and can be applied to a drill bit having three or more blades. Therefore, in the second embodiment, a three-blade type drill bit having three blades at the tip of the drill bit will be described.

[0027] Fig. 6 is a diagram showing the shape of the drill bit 1 in the second embodiment. Fig. 6 shows a three-blade type drill bit 1 having three blades at the tip of the drill bit. Note that in Fig. 6, as in Fig. 1, the right side of the figure is a connection part that is connected to a concrete drill shank with a dust collection function, and the left side of the figure is a drill tip part equipped with blades.

[0028] In the drill bit 1 of this embodiment, as shown in Fig. 6, three blades, blade 8a, blade 8b, and blade 8c, are provided at the tip of the drill bit. When the drill bit 1 is connected to a drill and the shaft 4 rotates, the blades 8a, 8b, and 8c rotate together with the shaft 4 to perform drilling work. In addition, as shown in Figs. 6(A) to (C), a drilling powder receiving groove 2 is provided between each blade, and a dust collection hole 3 is provided in the drilling powder receiving groove 2. Each of Figs. 6(A), 6(B), and 6(C) shows the drill bit 1 as viewed from the direction of each drilling powder receiving groove 2.

[0029] In Fig. 6(A), a drilling powder receiving groove 2 is provided between the blades 8a and 8b at the tip of the drill, and a dust suction hole 3 is provided in the drilling powder receiving groove 2. In Fig. 6(B), a drilling powder receiving groove 2 is provided between the blades 8b and 8c at the tip of the drill, and a dust suction hole 3 is provided in the drilling powder receiving groove 2. In Fig. 6(C), a drilling powder receiving groove 2 is provided between the blades 8c and 8a at the tip of the drill, and a dust suction hole 3 is provided in the drilling powder receiving groove 2. A carbide tip 5 is provided at the tip of the drill bit 1.

[0030] In the drill bit 1 of this embodiment, as in the first embodiment, the rod-shaped shaft 4 of the drill bit 1 has a section that is one step thinner between the tip side and the connection side. In the example shown in FIG. 6(A) to FIG. 6(C), the thickness of the shaft 4 in the middle part between the tip side 4a and the connection side 4b is thinner than the thickness of the shaft on the left side of 4a and the thickness of the shaft on the right side of 4b. In this way, by providing a step in the rod-shaped shaft part and making the shaft 4 one step thinner between the tip side and the connection side, it is possible to prevent the air flowing into the hole from being blocked even if the asphalt waterproofing material wrapped around and attached to the shaft 4 reaches a certain thickness. As a result, even if the waterproofing material is softened and becomes viscous due to frictional heat generated during the drilling operation and adheres to the shaft 4, the one-step thinner part of the shaft 4 serves as a step part for ventilation, so that the flow of air necessary for dust collection is prevented from being blocked, and the drilling operation can be performed continuously without impeding the intake of air into the hole. In addition, there is waterproofing material on the roof of a building that has already softened and become viscous due to direct sunlight, and even if this adheres to shaft 4, it is possible to prevent the inflow of air necessary for dust collection from being blocked.

[0031] In the drill bit 1 in the second embodiment, the axial position of the dust suction hole 3 provided in the drilling powder receiving groove 2 is different between Fig. 6(A), Fig. 6(B), and Fig. 6(C). As an example, in Fig. 6(A), the dust suction hole 3 is provided near the tip of the drilling powder receiving groove 2, in Fig. 6(B), the dust suction hole 3 is provided near the center of the drilling powder receiving groove 2, and in Fig. 6(C), the dust suction hole 3 is provided near the connection part of the drilling powder receiving groove 2. Thus, in the example shown in Fig. 6, the three dust suction holes 3 are arranged at different cross-sectional positions. When the diameter of the drill bit 1 is small, if the dust suction holes 3 are machined at the same cross-sectional position, it is easily affected by the strength reduction due to cross-sectional loss. Therefore, in the drill bit 1 in this embodiment, the position of the dust suction hole 3 is shifted in the axial direction, i.e., in the longitudinal direction of the shaft 4, to reduce the effect of the strength reduction.

[0032] In the drill bit 1 of this embodiment, a dust suction passage is provided inside the shaft 4 as a passage for the drilling powder, cuttings, etc., in order to suck up dust and the like such as drilling powder and cuttings through the dust suction hole 3. Figure 7 is a diagram showing the internal structure of the shaft 4 in the drill bit 1 shown in Figure 6 (B) by a broken line. As shown in Figure 7, a dust suction passage 7 is provided inside the shaft 4 so as to penetrate the inside of the shaft 4 in order to suck up the drilling powder, cuttings, etc. sucked in through the dust suction hole 3 toward the connection part of the drill bit 1.

[0033] Figure 8 is a cross-sectional view of the drill bit 1 shown in Figures 6(A), 6(B), and 6(C) cut perpendicularly to the axis 4 at the position of the dust suction hole 3. Figure 8(A) shows a cross-sectional view of the drill bit 1 shown in Figure 6(A) cut perpendicularly to the axis 4 at the position of the dust suction hole 3, Figure 8(B) shows a cross-sectional view of the drill bit 1 shown in Figure 6(B) cut perpendicularly to the axis 4 at the position of the dust suction hole 3, and Figure 8(C) shows a cross-sectional view of the drill bit 1 shown in Figure 6(C) cut perpendicularly to the axis 4 at the position of the dust suction hole 3.

[0034] As shown in Fig. 8(A), Fig. 8(B), and Fig. 8(C), the shaft 4 is provided with a drilling powder receiving groove 2 between the blade 8a and the blade 8b, between the blade 8b and the blade 8c, and between the blade 8c and the blade 8a. In the example shown in Fig. 8(A), a dust suction hole 3 is opened in the drilling powder receiving groove 2 provided between the blade 8a and the blade 8b, in the example shown in Fig. 8(B), a dust suction hole 3 is opened in the drilling powder receiving groove 2 provided between the blade 8b and the blade 8c, and in the example shown in Fig. 8(C), a dust suction hole 3 is opened in the drilling powder receiving groove 2 provided between the blade 8c and the blade 8a. These dust suction holes 3 are provided in a direction perpendicular to the axis and are connected to a dust suction passage 7 provided inside the shaft 4. In the present embodiment, the drilling powder receiving groove 2 has a curved shape, as shown in Fig. 8(A), Fig. 8(B), and Fig. 8(C).

[0035] In this way, in the drill bit 1 of this embodiment, the dust suction hole 3 is provided in the drilling powder receiving groove 2, so that the inner surface of the hole opened by drilling does not come into contact with the dust suction hole 3, and the dust suction hole 3 is not directly blocked. In addition, since insulation material and the like is not sucked in through the dust suction hole 3, it is possible to prevent the dust suction hole 3 and the dust suction passage 7 connected thereto from being blocked.

[0036] Fig. 9 is a schematic diagram showing a concrete drill shank 10 with a dust collection function to which a drill bit 1 in the second embodiment is connected. As shown in Fig. 9(A), the concrete drill shank 10 with a dust collection function has a connection part 11 for connecting the drill bit 1. In this embodiment, as shown in Fig. 9(B), the drill bit 1 can be connected to the concrete drill shank 10 with a dust collection function by connecting the connection part 11 of the concrete drill shank 10 with a dust collection function to the connection part 9 of the drill bit 1.

[0037] As shown by the dashed line in Fig. 10(A), the inside of the concrete drill shank 10 with the dust suction function is provided with a dust suction passage 12 for sucking up the above-mentioned drilling powder, cutting chips, etc. As shown in Fig. 10(B), when the drill bit 1 is connected to the concrete drill shank 10 with the dust suction function, the dust suction passage 7 of the drill bit 1 and the dust suction passage 12 of the concrete drill shank 10 with the dust suction function are connected inside. This allows the drilling powder, cutting chips, etc. sucked in through the dust suction hole 3 to be sucked in using the concrete drill shank 10 with the dust suction function. In Fig. 10, the dust suction passage provided inside is shown by the dashed line.

[0038] According to the second embodiment described above, the following advantageous effects can be obtained. (1) The drill bit 1 comprises a shaft 4 of the drill bit, a plurality of blades 8a, 8b, and 8c provided at the tip of the shaft 4, a drilling powder receiving groove 2 provided between the blades, and a dust suction hole 3 provided in each drilling powder receiving groove 2 so as to connect to a dust suction passage 7 provided inside the shaft 4. Since the dust suction hole 3 is provided in the drilling powder receiving groove 2 in this way, the inner surface of the hole opened by drilling does not come into contact with the dust suction hole 3, and the dust suction hole 3 can be prevented from being directly blocked. In addition, the asphalt waterproofing material melted by the frictional heat caused by the drilling work does not wrap around and adhere to the drilling powder receiving groove 2 processed in three places on the shaft 4, so that the dust suction hole 3 can be prevented from being blocked. Furthermore, since insulation material, waterproofing material, etc. are not sucked in through the dust suction hole 3, the dust suction passage 7 can be prevented from being blocked. In addition, the drilling powder of the asphalt waterproofing material wraps around and adheres to the rod-shaped shaft 4, preventing it from scattering. In addition, since the drilling work is performed while dust is being sucked through the dust suction hole 3, it is possible to prevent the drilling powder of concrete, etc. from scattering.

[0039] (2) The drill bit 1 has a step for ventilation created by narrowing the middle part of the shaft 4. This prevents the waterproofing material generated during the drilling operation and the viscous waterproofing material that softens due to frictional heat from the drill and wraps around and adheres to the shaft 4 from blocking the inflow of air needed for dust collection. In this way, by narrowing the rod-shaped shaft in one step, the asphalt waterproofing material that wraps around and adheres to the shaft does not block the air flowing into the hole even when it reaches a certain thickness, so drilling can be performed continuously without interfering with the intake of air into the hole.

[0040] (3) The dust suction holes 3 are arranged at different axial positions. As a result, if the drill bit has a small diameter and the dust suction holes 3 are machined at the same cross-sectional position, the strength is likely to be reduced due to cross-sectional loss. However, by displacing the positions of the dust suction holes 3 in the axial direction, i.e., the longitudinal direction of the shaft 4, as in the drill bit 1 of this embodiment, the influence of the reduction in strength can be reduced.

[0041] --Variations-- The drill bit according to the above embodiment can be modified as follows. (1) In the first embodiment described above, a two-blade type drill bit having two blades at the tip of the drill bit has been described. In the second embodiment described above, a three-blade type drill bit having three blades at the tip of the drill bit has been described. However, the number of blades at the tip of the drill bit is not limited to this as long as it is multiple, and the present invention is also applicable, for example, to a case where the drill bit has four or more blades.

[0042] (2) In the above-mentioned first and second embodiments, an example has been described in which the drilling powder receiving groove 2 has a curved shape. However, the shape of the drilling powder receiving groove 2 is not limited to this. For example, the drilling powder receiving groove 2 may be an angular groove or a V-shaped groove.

[0043] (3) In the above-described first and second embodiments, the dust suction hole 3 is provided in the drilling powder receiving groove 2 in a direction perpendicular to the axis. However, the direction of the dust suction hole 3 in the drilling powder receiving groove 2 is not limited to a direction perpendicular to the axis.

[0044] (4) In the above-described first and second embodiments, the drill bit is, for example, a drill bit attached to a concrete drill shank with a dust suction function. However, the drill bit is not limited to a drill bit attached to a concrete drill shank with a dust suction function.

[0045] The present invention is not limited to the configurations in the above-described embodiments as long as the characteristic functions of the present invention are not impaired. Also, the present invention may be configured by combining the above-described embodiments with a number of modified examples. [Explanation of symbols]

[0046] 1 Drill bit 2 Drilling powder receiving groove 3 Dust suction hole 4th axis 5 Carbide Tip 6a, 6b, 8a, 8b, 8c blade 7, 12 Dust suction passage 9, 11 Connection 10 Concrete drill shank with dust collection function

Claims

1. The shaft of the drill bit; A plurality of blades provided at the tip of the shaft; A groove for receiving drilling powder provided between the blades; A drill bit characterized in that each of the drilling powder receiving grooves has a dust suction hole provided so as to connect to a dust suction passage provided inside the shaft.

2. 2. The drill bit of claim 1, A drill bit characterized in that a step portion for ventilation is provided by narrowing the middle portion of the shaft.

3. The drill bit according to claim 1 or 2, The drill bit, wherein the dust suction holes are arranged at different positions in the axial direction.

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