Dust collection cover holder for hole-drilling device and dust collection cover device equipped therewith

Abstract

To improve stability in supporting a hole-drilling device while reducing the number of parts in a dust collection cover holder for the hole-drilling device.SOLUTION: A dust collection cover holder is mounted to a hole-drilling device which has a drill tool and a drill driving device to which the drill tool is attached at a shank portion and supports a dust collection cover. The dust collection cover holder is provided with: a holder plate that has a cover-support part for supporting the dust collection cover and a bearing fitting hole; and a slide bearing that is fitted into the bearing fitting hole of the holder plate. The slide ding bearing has: a cylindrical portion that has an insertion space through which the shank portion is inserted, and an inner peripheral surface that defines the insertion space and is in sliding surface contact with the outer peripheral surface of the shank portion; and a bottom plate part that includes a through hole through which the shank portion is inserted and a flat seating surface facing the base end side in the axial direction so as to be in surface contact with the tip surface of the drill driving device, and that closes the insertion space of the cylindrical portion from the base end side in the axial direction.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a dust-collection cover holder for a drilling device and a dust-collection cover device including the same. [Background technology]

[0002] Patent Document 1 discloses a dust-collection cover holder for a drilling device. The drilling device includes a drill tool having a cutting edge and a shank, and a drill driving device to which the drill tool is attached at the shank. The dust-collection cover holder is attached to the drilling device and supports a dust-collection cover. The dust-collection cover holder includes an oil-less metal disposed at its tip and a ball bearing disposed at its base. The ball bearing and the oil-less metal contact the shank and rotatably support the shank. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-259960 A Summary of the Invention [Problem to be solved by the invention]

[0004] The dust-collection cover holder has a large number of parts. In reducing the number of parts, there is room for improvement in terms of improving the stability when supporting the drilling device.

[0005] Therefore, an object of the present disclosure is to provide a dust collection cover holder for a drilling device that improves stability when supporting the drilling device while reducing the number of parts. [Means for solving the problem]

[0006] A dust collection cover holder according to one aspect of the present disclosure is attached to a drilling device including a drill tool having a cutting edge and a shank portion, and a drill driving device to which the drill tool is attached at the shank portion, and supports a dust collection cover, the dust collection cover holder comprising: a cover support portion that supports the dust collection cover; a holder plate having a bearing fitting hole; and a plain bearing fitted into the bearing fitting hole of the holder plate, and the side where the cutting edge is located in the axial direction of the plain bearing is defined as a tip end. the side where the drill driving device is located is defined as the base end side, and the side where the drill driving device is located is defined as the base end side, and the sliding bearing has a cylindrical portion having an insertion space through which the shank portion is inserted and an inner circumferential surface that defines the insertion space and is in slidable surface contact with the outer circumferential surface of the shank portion, an insertion hole through which the shank portion is inserted, and a flat seating surface facing the base end side in the axial direction so as to be in surface contact with the tip surface of the drill driving device, and a bottom plate portion that closes the insertion space of the cylindrical portion from the base end side in the axial direction.

[0007] According to one aspect of the present disclosure, the inner peripheral surface of the cylindrical portion of the plain bearing and the inner peripheral edge that defines the insertion hole of the bottom plate portion of the plain bearing are in stable contact with the drill tool, so that the dust collection cover holder is stably supported by the shank portion in the radial direction of the plain bearing. In addition, the tip surface of the drill driving device is pressed against the seat surface of the bottom plate portion of the plain bearing in surface contact, so that the dust collection cover holder is stably supported by the shank portion in the axial direction of the plain bearing. Therefore, it is possible to prevent the dust collection cover holder from shaking relative to the drilling device while reducing the number of parts. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a drilling device assembly according to an embodiment. [Diagram 2] FIG. 2 is a plan view of the dust-collection cover holder of FIG. [Diagram 3] FIG. 3 is a side view of the dust-collection cover holder of FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5]5 is an enlarged view of the dust-collecting cover device and its surroundings in FIG. 1, in which the dust-collecting cover device is cut at a location corresponding to line IV-IV in FIG. 3 to reveal the external appearance of the drill tool. [Figure 6] FIG. 6 is an enlarged cross-sectional view of the sliding bearing and its surrounding area in FIG. 5, showing the dust-collection cover device as well as the drill tool taken at a location corresponding to line IV-IV in FIG. [Figure 7] 7 is an enlarged cross-sectional view of the dust-collection cover holder taken along line IV-IV in FIG. 3 with the dust-proof cap fitted between the holder plate and the sliding bearing, and of the dust-proof cap and its surrounding area. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the drawings. In the following description, the direction in which the rotation axis AX of the drill tool 20 extends is defined as the axial direction and the up-down direction.

[0010] Fig. 1 is a schematic diagram showing a drilling device assembly 1 according to an embodiment. As shown in Fig. 1, the drilling device assembly 1 includes a drilling device 2 and a dust-collecting cover device 3 attached to the drilling device 2. The drilling device assembly 1 drills a drilling area Wa of a drilling target W using the drilling device 2 with the area Wa covered by the dust-collecting cover device 3.

[0011] In this embodiment, the drilling target W is a ceiling, and drilling work is performed with the cutting edge 28a (see FIG. 5) of the core drill 25 of the drilling device 2 facing upward. For example, when viewed from the top-bottom direction, the worker presses the tip of the bellows body 55 of the dust-collection cover 50 of the dust-collection cover device 3 against the drilling target W, with the dust-collection cover device 3 covering the drilling target Wa. At this time, the worker bends only a part of the bellows body 55 from its tip side to its base end side with his / her own hand to create a gap between the part and the drilling target W, thereby positioning the center drill 21 and the core drill 25 of the drilling device 2 with respect to the drilling target Wa while visually checking the drilling target Wa in the dust-collection cover 50. Then, the worker returns the partially bent bellows body 55 to its original state, completely covering the area Wa to be drilled with the dust-collecting cover device 3, and then presses down the operating part 15 of the drilling device 2 to rotate the center drill 21 and the core drill 25 to drill the area Wa to be drilled. By performing the drilling work as described above, dust generated during drilling is accumulated inside the dust-collecting cover device 3. Therefore, the worker can perform the drilling work without being covered in dust.

[0012] The drilling device 2 includes a drill driving device 10 and a drill tool 20 that is rotationally driven by the drill driving device 10 .

[0013] The drill driving device 10 includes an electric motor 11, which is a prime mover for rotating a drill tool 20, a reducer 12 adjacent to the tip side of the electric motor 11 and connected to a drive shaft 11a of the electric motor 11, and a housing 13 for accommodating the electric motor 11 and the reducer 12. The drill driving device 10 further includes a shank coupling part 14 provided on the tip side of the reducer 12 and connected to the reducer 12 via a transmission shaft 12a, an operation part 15 for driving the electric motor 11 when pressed by an operator, and a power cord 16 for connecting the electric motor 11 to a power supply source. The rotation speed of the power from the electric motor 11 is reduced by the reducer 12 and transmitted to the drill tool 20 via the transmission shaft 12a and the shank coupling part 14.

[0014] The drill tool 20 has a rod-shaped center drill 21 extending axially on the rotation axis AX, a cylindrical core drill 25 fixed to the center drill 21, and a shank portion 30 fixed to the center drill 21 and the core drill 25 and attached to the drill driving device 10. The drill tool 20 further has a fixture 40 (see FIG. 6 ) for fixing the center drill 21 to the shank portion 30, and a fixing mechanism 45 for fixing the core drill 25 to the shank portion 30.

[0015] As shown in FIG. 5, the center drill 21 is coaxial with the core drill 25, penetrates the core drill 25, and protrudes from the tip surface of the core drill 25. The core drill 25 includes a disk-shaped base plate portion 26 having a central hole through which the center drill 21 is inserted, and a side portion 27 protruding from the outer periphery of the base plate portion 26 toward the tip side in the axial direction and defining an internal space of the core drill 25 together with the base plate portion 26. The internal space of the core drill 25 is open toward the tip side of the core drill 25. The core drill 25 has a cutting portion 28 including a cutting edge 28a at its tip. In this embodiment, the cutting portion 28 includes a plurality of cutting edges 28a arranged in parallel in the circumferential direction of the core drill 25.

[0016] As shown in FIG. 6, the shank portion 30 has a first shaft portion 31 coupled to the shank coupling portion 14 of the drill driving device 10, a second shaft portion 32 adjacent to the first shaft portion 31 at the axial tip end side and having a larger diameter than the first shaft portion 31, and a third shaft portion 33 adjacent to the second shaft portion 32 at the axial tip end side and having a larger diameter than the second shaft portion 32. The first shaft portion 31 is a solid shaft, while the second shaft portion 32 and the third shaft portion 33 are hollow shafts. The second shaft portion 32 has a fixing hole 32a penetrating the second shaft portion 32 in the radial direction. The third shaft portion 33 has a bottom portion 34 adjacent to the second shaft portion 32, and a side portion 35 (see FIG. 6) that protrudes from the outer periphery of the bottom portion 34 toward the axial tip end side and defines an internal space of the third shaft portion 33 together with the bottom portion 34. The shank portion 30 further has a hole 36 in the central portion of the shank portion 30 when viewed in the axial direction, recessed from the tip surface of the bottom 34 of the third shaft portion 33 toward the base end side in the axial direction and extending to the base end of the second shaft portion 32.

[0017] The base end of the center drill 21 has a groove 21a recessed radially inward on its outer circumferential surface. The base end of the center drill 21 passes through the center hole of the core drill 25 and the internal space of the third shaft portion 33 of the shank portion 30, and fits into the hole 36 of the shank portion 30. At this time, the groove 21a of the base end of the center drill 21 faces the fixing hole 32a of the second shaft portion 32 of the shank portion 30. The fixing device 40 is inserted into the fixing hole 32a of the second shaft portion 32 and reaches the radially inner surface of the groove 21a of the base end of the center drill 21, and presses the base end of the center drill 21. As a result, the center drill 21 is fixed in the circumferential direction around the rotation axis AX so as to rotate integrally with the shank portion 30. The fixing device 40 is a bolt, a screw, or a pin.

[0018] 5, the fixing mechanism 45 has a sleeve mechanism 46 provided coaxially with the center drill 21 and the shank portion 30 so as to surround the base end of the center drill 21 and the side portion 35 (see FIG. 6) of the third shaft portion 33 of the shank portion 30, and a nut 47 screwed onto the male thread surrounding the center drill 21 on the tip side of the central hole of the base plate portion 26 of the core drill 25. The fixing mechanism 45 detachably fixes the core drill 25 to the shank portion 30 by using such a known structure.

[0019] The dust-collecting cover device 3 has a dust-collecting cover 50 and a dust-collecting cover holder 60 that is attached to the drilling device 2 (see FIG. 1) and supports the dust-collecting cover 50.

[0020] The dust-collecting cover 50 has a base body 51 attached to the dust-collecting cover holder 60, and a cylindrical bellows body 55 fixed to the base body 51. The base body 51 includes a supported portion 52 attached to a cover support portion 62 of a holder plate 61 (described later) of the dust-collecting cover holder 60. The supported portion 52 protrudes radially inward from its inner peripheral surface and has a locking protrusion 52a extending in the circumferential direction. The base body 51 is made of hard resin (e.g., high-density polyethylene). The bellows body 55 protrudes from the outer periphery of the base body 51 toward the tip side in the axial direction. The bellows body 55 is made of stretchable soft resin (e.g., low-density polyethylene).

[0021] In this embodiment, supported portion 52 of base body 51 has a plurality of (for example, four) locking protrusions 52a. In this embodiment, base body 51 further has an annular recess 53 recessed from the tip surface of its bottom toward the base end in the axial direction. In this embodiment, bellows body 55 has an annular protrusion 56 protruding from the inner peripheral edge of its bottom toward the base end in the axial direction. In this embodiment, bellows body 55 is fixed to base body 51 by fitting annular protrusion 56 of bellows body 55 into annular recess 53 of base body 51.

[0022] Fig. 2 is a plan view of the dust-collecting cover holder 60 in Fig. 1. Fig. 3 is a side view of the dust-collecting cover holder 60 in Fig. 1. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3. As shown in Figs. 2 to 4, the dust-collecting cover holder 60 has a holder plate 61 that is circular when viewed from the axial direction, a metal sliding bearing 70 that is fitted into a bearing fitting hole 63 of the holder plate 61, and a retaining ring 90 that is fitted into an annular groove portion 75 of the sliding bearing 70. In the following description, in the axial direction of the sliding bearing 70, the side where the core drill 25 (see Fig. 1) is located is defined as the tip side, and the side where the drill driving device 10 (see Fig. 1) is located is defined as the base side.

[0023] The holder plate 61 has a cover support portion 62 that supports the dust collection cover 50 (see FIG. 5), a bearing fitting hole 63 into which the plain bearing 70 is fitted, a circumferential protrusion portion 64 that faces the outer peripheral edge of a flange portion 74 (described later) of the plain bearing 70 in the radial direction of the plain bearing 70, and an annular protrusion portion 65 that protrudes toward the tip side in the axial direction at a position spaced radially outward from the plain bearing 70. The outer peripheral edge of the holder plate 61 has a plurality of (e.g., eight) recesses 66 that are aligned in the circumferential direction when viewed from the axial direction. The inner peripheral portion of the holder plate 61 is sandwiched in the axial direction between the flange portion 74 (described later) of the plain bearing 70 and a retaining ring 90. The cover support portion 62 has a locking groove portion 62a that is recessed radially inward on the outer peripheral surface of the holder plate 61 and extends in the circumferential direction. The locked groove portion 62a is locked to the locking protrusion 52a (see FIG. 5) of the base body 51 (see FIG. 5) of the dust-collection cover 50, whereby the base body 51 is fixed to the holder plate 61. The holder plate 61 is made of hard resin (for example, nylon 66).

[0024] In this embodiment, the cover support part 62 has a plurality of (for example, four) locked groove parts 62a spaced apart in the circumferential direction of the holder plate 61. In this embodiment, the locked groove part 62a has an introduction part recessed from the outer peripheral surface of the side part of the holder plate 61 radially inward of the holder plate 61 and extending in the axial direction from the tip of the side part to the center part, and an locked part extending in the circumferential direction from the base end side of the introduction part. The locking protrusion part 52a (see FIG. 5) of the base body 51 (see FIG. 5) is introduced from the tip of the introduction part of the locked groove part 62a into the introduction part, slides inside the introduction part toward the base end side in the axial direction, and then slides inside the locked part in the circumferential direction of the holder plate 61. As a result, the locking protrusion part 52a of the base body 51 is locked to the locked groove part 62a of the holder plate 61, and the base body 51 is fixed to the holder plate 61.

[0025] The plain bearing 70 has a cylindrical portion 71 and a bottom plate portion 80 that closes an insertion space 72 of the cylindrical portion 71 from the base end side in the axial direction. The cylindrical portion 71 has an insertion space 72 through which the shank portion 30 (see FIG. 6) is inserted, and an inner peripheral surface 73 that defines the insertion space 72 and is in surface contact with the outer peripheral surface of the shank portion 30 so as to be able to slide freely. The bottom plate portion 80 has an insertion hole 86 through which the shank portion 30 is inserted, and a flat seat surface 87 facing the base end side in the axial direction so as to be in surface contact with the tip surface of the drill driving device 10. The plain bearing 70 further has a flange portion 74 that protrudes from the cylindrical portion 71 radially outward of the plain bearing 70, and an annular groove portion 75 that is formed on the outer peripheral surface of the cylindrical portion 71 and extends in the circumferential direction at a position spaced from the flange portion 74 on the tip side in the axial direction. The flange portion 74 protrudes radially outward from a base end side portion of the cylindrical portion 71, and the retaining ring 90 is disposed on the tip side of the flange portion 74. The retaining ring 90 is fitted in the annular groove portion 75.

[0026] FIG. 5 is an enlarged view of the dust-collecting cover device 3 and its surroundings in FIG. 1, in which the dust-collecting cover device 3 is cut at a location corresponding to the line IV-IV in FIG. 3 to show the appearance of the drill tool 20. FIG. 6 is an enlarged view of the sliding bearing 70 and its surroundings in FIG. 5, in which the dust-collecting cover device 3 and the drill tool 20 are cut at a location corresponding to the line IV-IV in FIG. 3. As shown in FIG. 5 and FIG. 6, the inner peripheral edge defining the insertion hole 86 of the bottom plate portion 80 of the sliding bearing 70 is configured to slidably contact the outer peripheral surface of the first shaft portion 31 of the shank portion 30. The inner peripheral surface 73 of the cylindrical portion 71 of the sliding bearing 70 is configured to slidably contact the outer peripheral surface of the second shaft portion 32 of the shank portion 30. The tip surface of the cylindrical portion 71 of the sliding bearing 70 at the tip side in the axial direction is configured to be in surface contact with the base end surface of the third shaft portion 33 at the base end side in the axial direction. A seat surface 87 of the bottom plate portion 80 of the sliding bearing 70 on the base end side in the axial direction is configured to be in surface contact with a tip surface of the shank coupling portion 14 of the drill driving device 10 on the tip side in the axial direction.

[0027] According to the configuration described above, the inner peripheral surface 73 of the cylindrical portion 71 of the plain bearing 70 and the inner peripheral edge defining the insertion hole 86 of the bottom plate portion 80 of the plain bearing 70 come into stable contact with the drill tool 20, so that the dust collection cover holder 60 is stably supported by the shank portion 30 in the radial direction of the plain bearing 70. In addition, the tip surface of the drill driving device 10 is pressed against the seat surface 87 of the bottom plate portion 80 of the plain bearing 70 in surface contact, so that the dust collection cover holder 60 is stably supported by the shank portion 30 in the axial direction of the plain bearing 70. Therefore, it is possible to prevent the dust collection cover holder 60 from shaking relative to the drilling device 2 while reducing the number of parts.

[0028] Since the sliding bearing 70 is made of metal, stable support of the shank portion 30 by the sliding bearing 70 can be easily achieved.

[0029] The tip surface of the drill driving device 10 presses the seat surface 87 of the bottom plate portion 80 of the plain bearing 70 against the tip side in the axial direction, and the base end surface of the third shaft portion 33 of the shank portion 30 presses the tip surface of the cylindrical portion 71 of the plain bearing 70 against the base end side in the axial direction. Thus, the dust collection cover holder 60 is stably supported by the shank portion 30 in the axial direction of the plain bearing 70. In addition, since the plain bearing 70 supports both the first shaft portion 31 and the second shaft portion 32, the dust collection cover holder 60 is also stably supported by the shank portion 30 in the radial direction of the plain bearing 70.

[0030] Since the inner periphery of the holder plate 61 is sandwiched in the axial direction between the flange portion 74 and the retaining ring 90 of the sliding bearing 70, the holder plate 61 can be stably assembled to the sliding bearing 70 and can be easily removed from the sliding bearing 70.

[0031] Since the holder plate 61 has a circumferential protrusion portion 64 that radially faces the outer peripheral edge of the flange portion 74 of the sliding bearing 70, the flange portion 74 is positioned radially relative to the holder plate 61, thereby further stabilizing the positional relationship between the holder plate 61 and the sliding bearing 70.

[0032] Since the outer peripheral edge of the holder plate 61 has a plurality of recesses 66 when viewed from the axial direction, an operator can easily grip the outer peripheral edge of the holder plate 61, improving the workability of maintenance work such as replacing the dust collection cover 50.

[0033] The technology of the present disclosure is not limited to the above-mentioned configuration. Fig. 7 is a cross-sectional view of the dust-collection cover holder 60 cut at a position corresponding to the line IV-IV in Fig. 3 with the dust-proof cap 95 fitted between the holder plate 61 and the plain bearing 70, and enlarging the dust-proof cap 95 and its surrounding area. As shown in Fig. 7, the dust-collection cover holder 60 may further include an annular dust-proof cap 95 fitted between the annular protrusion 65 and the plain bearing 70. As a result, even if a situation occurs in which dust leaks from a small gap between the plain bearing 70 and the holder plate 61, such leakage can be prevented by the dust-proof cap 95.

[0034] In the above embodiment, a description has been given of the case where the sliding bearing 70 is made of metal. However, this is not limited to this case, and the sliding bearing 70 may be made of a material other than metal as long as the material has wear resistance.

[0035] In the above embodiment, the drill tool 20 has been described as having the rod-shaped center drill 21 and the cylindrical core drill 25. However, the present invention is not limited to this case, and the drill tool 20 may be, for example, a rod-shaped drill including a shank portion 30 without having the cylindrical core drill 25.

[0036] In the above embodiment, a case has been described in which the dust-collection cover 50 includes the supported portion 52 attached to the cover support portion 62 of the holder plate 61. However, the present invention is not limited to this case, and the dust-collection cover 50 may be fixed to the holder plate 61 using the fixing device 40.

[0037] In the above embodiment, the case where the bellows body 55 of the dust collection cover 50 is made of an expandable soft resin (for example, low-density polyethylene) has been described. However, the present invention is not limited to this case, and the bellows body 55 may be made of an expandable hard resin (for example, high-density polyethylene) or other materials.

[0038] In the above embodiment, a case has been described in which the flange portion 74 of the sliding bearing 70 is located closer to the base end than the retaining ring 90. However, this is not limited to this case, and the flange portion 74 may be located closer to the tip end than the retaining ring 90.

[0039] In the above embodiment, the case where the cover support portion 62 of the holder plate 61 is circular when viewed from the axial direction has been described. However, the present invention is not limited to this case, and the cover support portion 62 may be polygonal or of another shape as long as it can support the dust collection cover 50 and can fit the sliding bearing 70 when viewed from the axial direction.

[0040] Each of the following aspects is a disclosure of a preferred embodiment. [Aspect 1] A dust collection cover holder is attached to a drilling device including a drill tool having a cutting edge and a shank portion, and a drill driving device to which the drill tool is attached at the shank portion, and supports a dust collection cover, a holder plate having a cover support portion for supporting the dust collection cover and a bearing fitting hole; a sliding bearing fitted in the bearing fitting hole of the holder plate, In the axial direction of the sliding bearing, the side on which the cutting edge is located is defined as the tip side, and the side on which the drill driving device is located is defined as the base side, The sliding bearing is a cylindrical portion having an insertion space through which the shank portion is inserted and an inner peripheral surface that defines the insertion space and is in slidable surface contact with an outer peripheral surface of the shank portion; a bottom plate portion having an insertion hole through which the shank portion is inserted and a flat seat surface facing the base end side in the axial direction so as to be in surface contact with a tip surface of the drill driving device, the bottom plate portion closing the insertion space of the cylindrical portion from the base end side in the axial direction; A dust collection cover holder for a drilling device, comprising: [Aspect 2] 2. The dust-collection cover holder for a drilling device according to claim 1, wherein the sliding bearing is made of metal. [Aspect 3] the shank portion has a first shank portion coupled to the drill driving device, a second shank portion adjacent to the first shank portion at the tip side in the axial direction and having a larger diameter than the first shank portion, and a third shank portion adjacent to the second shank portion at the tip side in the axial direction and having a larger diameter than the second shank portion, an inner peripheral edge of the bottom plate portion that defines the insertion hole is configured to slidably contact an outer peripheral surface of the first shaft portion; The inner circumferential surface of the cylindrical portion is configured to be in slidable surface contact with the outer circumferential surface of the second shaft portion, A dust collection cover holder for a drilling device as described in aspect 1 or 2, wherein the tip surface of the cylindrical portion at the tip side in the axial direction is configured to be in face-to-face contact with the base end surface of the third shaft portion at the base end side in the axial direction. [Aspect 4] Further provided with a retaining ring; The sliding bearing is A flange portion protruding from the cylindrical portion radially outward of the sliding bearing; an annular groove portion formed on an outer circumferential surface of the cylindrical portion at a position spaced from the flange portion in the axial direction and extending in a circumferential direction; and The retaining ring is fitted into the annular groove, A dust-collection cover holder for a drilling device according to any one of aspects 1 to 3, wherein an inner periphery of the holder plate is sandwiched between the flange portion and the retaining ring in the axial direction. [Aspect 5] A dust-collection cover holder for a drilling device according to aspect 4, wherein the holder plate further has a peripheral protrusion portion on an outer circumferential edge of the flange portion facing in the radial direction. [Aspect 6] A dust-collection cover holder for a drilling device according to any one of aspects 1 to 5, wherein the outer peripheral edge of the holder plate has a plurality of recesses when viewed from the axial direction. [Aspect 7] Further provided with a circular dust cap; The holder plate further has an annular convex portion protruding toward the tip side in the axial direction at a position spaced radially outward from the sliding bearing, A dust-collection cover holder for a drilling device according to any one of aspects 1 to 6, wherein the dust-proof cap is fitted between the annular convex portion and the sliding bearing. [Aspect 8] The dust-collection cover holder according to any one of aspects 1 to 7; A dust-collection cover supported by the dust-collection cover holder, The dust collection cover is a base body including a supported portion attached to the cover support portion of the holder plate of the dust-collection cover holder; a cylindrical bellows body fixed to the base body and protruding from an outer periphery of the base body toward the tip side in the axial direction; A dust collection cover device having the above structure. [Explanation of symbols]

[0041] 1. Drilling device assembly 2 Drilling device 3 Dust collection cover device 10 Drill drive unit 20 Drill tools 28a cutting edge 30 Shank 31 First shaft 32 Second shaft 33 Third shaft 50 Dust collection cover 51 Base body 52 Supported part 55 Bellows 60 Dust collection cover holder 61 Holder plate 62 Cover support part 63 Bearing fitting hole 64 Circumferential protrusion 65 Circular convex part 66 Recess 70 Plain bearing 71 Cylindrical part 72 Insertion space 73 Inner peripheral surface 74 Flange 75 Annular groove 80 Bottom plate part 86 Insertion hole 87 Seat 90 Retaining ring 95 Dust Cap

Claims

1. A dust collection cover holder is attached to a drilling device including a drill tool having a cutting edge and a shank portion, and a drill driving device to which the drill tool is attached at the shank portion, and supports a dust collection cover, a holder plate having a cover support portion for supporting the dust collection cover and a bearing fitting hole; a sliding bearing fitted in the bearing fitting hole of the holder plate, In the axial direction of the sliding bearing, the side on which the cutting edge is located is defined as the tip side, and the side on which the drill driving device is located is defined as the base side, The sliding bearing is a cylindrical portion having an insertion space through which the shank portion is inserted and an inner peripheral surface that defines the insertion space and is in slidable surface contact with an outer peripheral surface of the shank portion; a bottom plate portion having an insertion hole through which the shank portion is inserted and a flat seat surface facing the base end side in the axial direction so as to be in surface contact with a tip surface of the drill driving device, the bottom plate portion closing the insertion space of the cylindrical portion from the base end side in the axial direction; A dust collection cover holder for a drilling device, comprising:

2. 2. The dust-collecting cover holder for a drilling device according to claim 1, wherein the sliding bearing is made of metal.

3. the shank portion has a first shank portion coupled to the drill driving device, a second shank portion adjacent to the first shank portion at the tip side in the axial direction and having a larger diameter than the first shank portion, and a third shank portion adjacent to the second shank portion at the tip side in the axial direction and having a larger diameter than the second shank portion, an inner peripheral edge of the bottom plate portion that defines the insertion hole is configured to slidably contact an outer peripheral surface of the first shaft portion; The inner circumferential surface of the cylindrical portion is configured to be in slidable surface contact with the outer circumferential surface of the second shaft portion, A dust collection cover holder for a drilling device as described in claim 1, wherein the tip surface of the cylindrical portion at the tip side in the axial direction is configured to be in face contact with the base end surface of the third shaft portion at the base end side in the axial direction.

4. Further provided with a retaining ring; The sliding bearing is A flange portion protruding from the cylindrical portion radially outward of the sliding bearing; an annular groove portion formed on an outer circumferential surface of the cylindrical portion at a position spaced from the flange portion in the axial direction and extending in a circumferential direction; and The retaining ring is fitted into the annular groove, 4. The dust-collection cover holder for a drilling device according to claim 1, wherein an inner periphery of the holder plate is sandwiched between the flange portion and the retaining ring in the axial direction.

5. 5. The dust-collection cover holder for a drilling device according to claim 4, wherein the holder plate further has peripheral protrusions on an outer circumferential edge of the flange portion so as to face each other in the radial direction.

6. 4. The dust-collection cover holder for a drilling device according to claim 1, wherein an outer peripheral edge of the holder plate has a plurality of recesses when viewed from the axial direction.

7. Further provided with a circular dust cap; The holder plate further has an annular convex portion protruding toward the tip side in the axial direction at a position spaced radially outward from the sliding bearing, The dust-collection cover holder for a drilling device according to claim 1 , wherein the dust-proof cap is fitted between the annular convex portion and the sliding bearing.

8. The dust-collection cover holder according to any one of claims 1 to 3, A dust-collection cover supported by the dust-collection cover holder, The dust collection cover is a base body including a supported portion attached to the cover support portion of the holder plate of the dust-collection cover holder; a cylindrical bellows body fixed to the base body and protruding from an outer periphery of the base body toward the tip side in the axial direction; A dust collection cover device having the above structure.

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