JP2009241158A - Boring tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently collect dust with small suction force and effectively prevent the dust from leaking outside in a boring tool including a dust collector for collecting the dust generated from a workpiece bored by a tip tool while blowing the air. <P>SOLUTION: The boring tool comprises a motor, a transmission drive for transmitting turning force of the motor to rotate the tip tool, and the dust collector for collecting the dust occurring from the workpiece bored by the tip tool and also blowing the air against the vicinity of a part to be bored. The tool is equipped with a filter means for filtering the air containing the collected dust, and a centrifugal fan 14 for taking in the filtered air and sending it out in a circumferential direction. The fan 14 is located in a housing 2a having formed an air flow feeding port 36 for circulating a part of the intake air to the dust collector for blowing and exhaust ports 35a and 35b for exhausting the remaining air to the outside. The exhaust ports 35a and 35b are provided backward from the air flow feeding port 36 in the rotation direction with respect to the rotation direction of the centrifugal fan 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a drilling tool that is driven by an electric motor, an engine, or the like in order to open a drilling hole, and in particular, a dust collecting device that collects dust generated from a work material drilled by a tip tool while blowing air. The present invention relates to a drilling tool that can be mounted.

  Drilling tools are widely used to drill holes in stone such as concrete and brick. A drilling tool is a tool for making a drilled hole in a work material by driving a tip tool such as a drill blade, and includes a general rotary drill, a hammer drill that rotates and strikes a drill blade, and a vibration drill. Since dust is generated when a drilling operation is performed using a drilling tool, an operator may wear a dust mask, protective glasses, or the like to perform the operation. In recent years, in order to remove dust generated during work, a device provided with a dust collecting device for sucking up dust has been widely used.

  For example, in Patent Document 1, a dust suction device that sucks dust generated near the tip of a drill by providing a dust suction cover to which a dust channel is connected to an electric drill device and sucking air by an external dust collector. It is disclosed.

Japanese Utility Model Publication No. 6-32248

  In the apparatus described in Patent Document 1, dust generated during drilling moves to the inside of the dust cover by the spiral structure of the drill and is sucked by an external dust collector. Some dust remains without being sucked even in the head, and it is difficult to suck the dust completely, resulting in suction leakage.

  It is an object of the present invention to efficiently collect dust with a small suction force and to allow dust to leak to the outside in a drilling tool having a suction port that sucks air together with dust and a blowout port that blows air. It is to be able to prevent effectively.

  Another object of the present invention is to secure a sufficient amount of air blown to the vicinity of the perforation hole to improve the dust collection efficiency of the dust generated during the perforation work, and also to remove dust remaining in the perforation hole after the perforation work. It is to improve the work site and the worker's environment by realizing an improved drilling tool.

  Still another object of the present invention is to provide a drilling tool that can efficiently realize an air flow from a suction port of a dust collector and a blower that sends air to an outlet with a single fan.

  Of the inventions disclosed in the present application, typical features will be described as follows.

  According to one aspect of the present invention, a drive source such as an electric motor, a transmission drive unit that transmits the rotational force of the drive source to rotate the tip tool, and dust generated from a work material that is drilled by the tip tool. A drilling tool having a dust collecting device that collects dust and blows air in the vicinity of a hole to be drilled, and filter means for filtering the dust-mixed air and the filtered air in the circumferential direction. A centrifugal fan to send out was provided, and the centrifugal fan was formed with an air supply port for sending a part of the air taken in to the dust collector for blowing, and an exhaust port for discharging the remaining air to the outside It is arranged in a housing having a substantially cylindrical inner wall, and the distance to the discharge port in the front direction of rotation of the airflow port fan is larger than the distance to the discharge port in the rear direction of rotation of the airflow port. didThe centrifugal fan can be attached to the rotating shaft of the electric motor and incorporated in the housing of the drilling tool. This housing may be integral with the housing of the main body of the drilling tool, may be a housing of the motor unit, or may be a dedicated housing for housing the centrifugal fan.

  According to another feature of the present invention, the discharge ports are provided at a plurality of locations of the housing, and the discharge ports may be arranged at a rotation angle of 180 degrees behind the air flow port in the rotation direction, for example, the first discharge port. The outlet can be disposed within a rotation angle of 90 degrees behind the airflow port and the second discharge port can be disposed within a rotation angle of 90 to 180 degrees behind the airflow port.

  According to another feature of the present invention, the housing has a substantially cylindrical inner wall surrounding the periphery of the centrifugal fan, and the distance between the outer peripheral end of the centrifugal fan and the inner wall in front of the rotation angle of the airflow port is the airflow The distance near the mouth is the farthest, and the distance between the outer peripheral edge and the inner wall is close on the opposite side of the airflow port through the centrifugal fan shaft, and the distance gradually decreases from near the airflow port toward the opposite side. To. This may be achieved by forming the inner wall of the housing so that the central axis of the inner wall of the cylindrical housing is offset toward the air flow port side with respect to the rotational axis of the centrifugal fan. This configuration is preferred when the centrifugal fan housing is molded integrally with the body housing of the drilling tool. Conversely, the centrifugal fan may be arranged in the housing so that the rotational axis of the centrifugal fan is shifted from the central axis of the inner wall to the side opposite to the air flow port.

  According to another aspect of the present invention, a guide portion that protrudes toward the center of the centrifugal fan is formed on the inner wall of the housing on the rear side of the airflow port. The shape of the guide portion may be determined in consideration of the rectification effect in order to guide as much airflow generated by the centrifugal fan as possible to the airflow port.

  According to still another feature of the present invention, the air supply port is provided behind the centrifugal fan in the rotation direction in the housing in the tip tool mounting direction.

  According to the first aspect of the present invention, the distance to the discharge port at the front of the airflow port in the rotation direction of the fan is larger than the distance to the discharge port at the rear of the airflow port in the rotation direction. The pressure can be increased in the front, a strong airflow can be sent to the airflow port, and the dust collector can efficiently collect dust with a small suction force, effectively preventing dust from leaking outside. it can.

  According to the second aspect of the present invention, at least two discharge ports are provided, and the distance to the discharge port at the front of the centrifugal fan in the rotation direction of the air flow port is the distance to the discharge port at the rear of the rotation direction of the air flow port. Therefore, it is possible to provide a discharge port on the side and the rear of the body housing of the drilling device.

  According to the third aspect of the present invention, since the electric motor is used as the drive source and the centrifugal fan is provided on the rotating shaft of the electric motor, the centrifugal fan is provided outside the main body housing, and the centrifugal fan drive source is provided. Since it is not necessary, the centrifugal fan can be integrally formed in the main body housing, and a compact drilling tool can be realized.

  According to the fourth aspect of the present invention, the discharge ports are provided at a plurality of locations of the housing, and all of them are disposed within the rotation angle of 180 degrees behind the air flow port in the rotation direction. A limited amount of part can be sent to the airflow port at high speed and high pressure.

  According to the fifth aspect of the present invention, the first discharge port is located within a rotation angle of 90 degrees behind the airflow port, and the second discharge port is rotated about 90 degrees behind the airflow port. Unlike the case of only the side or only after the housing, the pressure can be dispersed and discharged from the discharge port.

  According to the sixth aspect of the present invention, the distance between the outer peripheral end of the centrifugal fan and the inner wall in front of the rotation angle of the airflow port is the farthest near the airflow port, and from the airflow port through the axis of the centrifugal fan. On the opposite side, the distance was gradually reduced so that high-pressure air could move between the circumferential edge and the inner wall, and the high pressure could send a strong air flow to the airflow port. it can.

  According to the seventh aspect of the invention, since the inner wall of the housing is formed so that the central axis of the cylindrical housing is offset toward the air flow port side with respect to the rotation axis of the centrifugal fan, the shape of the inner wall is changed. You can adjust the strength of the airflow to the airflow port simply by changing it.

  According to the eighth aspect of the present invention, since the guide portion protruding in the center direction of the centrifugal fan is formed on the rear side of the air flow port, it is possible to guide the wind from the centrifugal fan to the air flow port by the guide portion. Therefore, it is possible to more efficiently guide the wind to the airflow port and to further increase the strength of the airflow to the airflow port.

  According to the invention described in claim 9, since there is a housing in the tip tool mounting direction in front of the airflow port in the rotation direction, the pressure can be increased in front of the airflow port using the housing. A strong air flow can be sent to the air supply port by high pressure.

  According to the tenth aspect of the present invention, since the pressure in front of the airflow port is increased in front of the airflow port fan in the rotation direction, a strong airflow can be sent to the airflow port. The dust collector can efficiently collect dust with a small suction force, and can effectively prevent dust from leaking to the outside.

  According to the eleventh aspect of the present invention, since the centrifugal fan is arranged in the housing so that the rotational axis of the centrifugal fan is shifted from the central axis of the inner wall of the housing to the side opposite to the air flow port, the centrifugal fan is shifted for each installation position of the motor. The dust collector can efficiently collect dust with a small suction force and effectively prevent the dust from leaking outside, because it can send a strong air flow to the air supply port without changing the shape of the housing. Can do.

  According to the twelfth aspect of the present invention, the centrifugal fan is mounted so that the distance between the centrifugal fan and the inner wall is the longest in the vicinity of the airflow port, and gradually approaches from the airflow port toward the front in the rotation direction. A strong air flow can be sent to the air flow port.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

  Hereinafter, a drilling tool according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a side view of a drilling tool showing an embodiment of the present invention, FIG. 2 is a side view showing a state in use thereof, and FIG. 3 is for explaining the air flow in the dust collecting adapter 10. FIG.

    The hammer drill main body 1 has four modes or any one of a rotation / blow mode, a rotation mode, a blow mode, and a neutral mode as operation modes, and the housing 2 includes a drive unit including a motor 18. A striking mechanism, a rotation transmission mechanism, and a switching mechanism are incorporated. A handle 3 is provided at the rear end of the housing 2 (in this specification, as shown in FIG. 1, front and rear and up and down directions are defined. The same applies hereinafter), and the handle 3 is provided with a power switch 4. The power supply electric cord 5 is connected to the power supply. A dial-like switching member 6 for switching the operation mode is rotatably provided on the side of the housing 2. A tip tool 26 is attached to the tip of the hammer drill 1, and the tip tool 26 receives a striking force and / or a rotating force to perform a required work on the work material 8.

  With reference to FIG. 1, a description will be given of a process of collecting dust generated during operation in the rotation / striking mode of the operation mode and the rotation mode. In the drilling work on the work material 8, the operator holds the handle 3 of the hammer drill 1 and operates the power switch 4 to drive the motor 18, and the hammer drill main body 1 based on the driving force of the motor 18. The tip tool 26 attached to the tip of the tool is rotated and hit. The operator holds the handle 3 of the hammer drill body 1 and presses the hammer drill 1 in the direction of the work material 8, whereby the tip tool 26 crushes the work material 8 and creates a hole in the work material 8.

  The tip tool 26 has a tip portion 26a that crushes the work material 8, and a spiral portion 26b that has a function of moving dust generated by crushing the work material 8 within the hole. The dust generated from the tip portion 26a of the tip tool 26 during operation moves into the dust collecting adapter 10 together with the rotation of the tip tool 26 and the shape of the spiral portion 26b. The dust that has moved into the dust collecting adapter 10 is guided to the dust channel 11 from the suction port 10b by the suction force generated by the dust collecting fan 14 provided on the rotating shaft 19 of the motor 18 in accordance with the arrow, and is collected. In the dust collection case 12 provided in the housing 33 of the apparatus, the filter 13 is separated and filtered into air and dust by passing through the filter 13, and the dust is stored in the dust collection case 12. The dust collecting case 12 is preferably detachable. By removing the dust collecting case 12, accumulated dust can be discarded, and the filter 13 can be cleaned or replaced. It becomes.

  On the other hand, the separated clean air reaches the intake port (not shown) in the axial direction of the dust collecting fan 14 through the air passage 15, and a part of the air circulates to the dust collecting adapter 10 by the dust collecting fan 14. The rest is discharged from the discharge port to the outside of the hammer drill body 1. The structure near the dust collecting fan 14 will be described later.

  A motor 18 is provided in the integrated housing 2 as a power source for driving the tip tool 26 inside the hammer drill body 1. When the tip tool 26 is driven, the motor 18 rotates and generates heat. In order to suppress the heat generation of the motor 18, a cooling fan 17 is provided on the rotating shaft 19 of the motor 18, and cooling air is sucked from a cooling air intake port (not shown) provided in the tail cover 16 by the suction force of the cooling fan 17. Then, according to the arrow, the cooling air cools the motor 18. After cooling the motor, the cooling air reaches the cooling fan 17 and is discharged to the outside of the hammer drill body 1 through a discharge port (not shown).

  The dust collection adapter 10 is held by a slider 31 attached to the hammer drill main body 1, and a spring 32 and an extendable dust flow path 11 are provided inside the slider 31, and the dust collection adapter is configured by the configuration of the spring 32 and the slider 31. 10 is biased in the direction of the work material 8. During the drilling operation, the hammer drill body 1 moves in the direction of the work material 8 as the drill hole becomes deeper. The dust collecting adapter 10 is biased by the spring 32 in the direction of the work material 8, but as the hammer drill body 1 moves in the direction of the work material 8 during drilling, the spring 32 is compressed and contracted, and the slider 31. By contracting, the dust collection adapter 10 always contacts the work material 8 and maintains a certain positional relationship. The slider 31 is composed of two members, and the length of the slider 31 contracts when one member enters the other member. As described above, since the slider 31 can be expanded and contracted, it is possible to collect dust corresponding to the depth of the hole. Further, the slider 31 can be fixed to extend and contract at an arbitrary position by the lock mechanism 41.

  Dust generated during the drilling operation moves into the dust collecting adapter 10 by the spiral structure of the tip tool 26 and is sucked together with air from the suction port 10 b by the suction force of the dust collecting fan 14. As shown in FIG. 3, at the time of drilling work, the air blown out from the air outlet 10a that discharges air is sent into the dust collecting adapter 10 to generate an air flow in the vicinity of the drill hole, thereby improving the dust collecting ability. Can be achieved. It is preferable that the amount of air blown out is smaller than the amount of air sucked. This is because the surrounding atmosphere is sucked from the vicinity of the through hole (hole through which the tip tool 26 is penetrated) of the dust collecting adapter 10, so that it is possible to satisfactorily prevent dust from being scattered around by sucking the surrounding atmosphere. it can.

  After completion of the drilling operation, part of the dust often remains in the drill hole. Therefore, as shown in FIG. 2, the operator brings the air outlet 10 a of the dust collection adapter 10 close to the perforation hole after the perforation hole is generated, and operates the power switch 4 to drive the motor 18 and the dust collection fan 14. Rotate. At this time, the tip tool 26 also rotates together. However, since the tip portion 26a is not in contact with the work material 8, the work material 8 is not damaged. It is preferable to set the maximum length of the slider 31 so that the positional relationship between the distal end portion 26a and the work material 8 is not in contact as shown in FIG.

  The air flow inside the hammer drill main body 1 reaches the dust collecting fan 14 from the air passage 15 and is discharged to the outside of the hammer drill main body 1 through a discharge port (not shown), and a part is recirculated to the dust collecting adapter 10. The

  Next, the structure near the dust collecting fan 14 will be described in detail with reference to FIGS. FIG. 4 is a cross-sectional view taken along a line AA in FIG. The dust collection fan 14 is a centrifugal fan, and sucks air flowing in from the air passage 15 through an intake port (not shown) formed in the axial direction and blows it in the circumferential direction by the rotational force of the blades. . The air flow to be blown is raised, for example, in the direction of arrow 51 in FIG. It is done. The remaining air flow is discharged to the outside as indicated by arrows 53 and 54 from the first discharge port 35a and the second discharge port 35b formed in the housing 2a. Here, in this embodiment, the housing 2a is a part of the housing 2 of the hammer drill main body 1, and is made of integrally molded plastic.

  The air that has flowed into the air flow port 36 flows into the dust collection adapter 10 via the guide channel 20. The guide channel 20 is located beside the dust channel 11 in the vicinity of the air flow port 36 of FIG. 4, but the slider 31 is configured to be positioned above the dust channel 11. However, it is not necessary to limit to this arrangement | positioning, You may make it coaxially arrange | position the dust flow path 11 inside, and arrange | position the guide flow path 20 outside.

  In FIG. 4, two discharge ports are provided in the rotation direction of the dust collecting fan 14 (clockwise in the figure), and both the first discharge port 35 a and the second discharge port 35 b are behind the air flow port 36. Placed in. Here, the front refers to the direction indicated by the arrow 55 when viewed from the airflow port 36 when the reference line 57 is drawn from the airflow port 36 toward the center point 60 of the fan as shown in the conceptual diagram of FIG. Say the position. Similarly, the rear means a position in the direction indicated by the arrow 56 when viewed from the air supply port 36. It should be noted that when the rotational direction of the dust collecting fan 14 is opposite to that shown in the drawing, the front side and the rear side are opposite.

  According to the definition of FIG. 5, the first discharge port 35 a and the second discharge port 35 b are both located rearward when viewed from the air flow port 36. As in the dust collection fan 14 according to the present embodiment, the fan that generates the flow of airflow by the turning force has the highest opening at the farthest side. Since the shape of the path for flowing into the dust collecting adapter 10 is complicated, the inflow resistance is high, and high pressure is required to efficiently blow air. Therefore, by setting the air flow port 36 in front of the discharge port 35 in the rotation direction of the dust collecting fan 14, the air flow can flow into the dust collecting adapter 10 most efficiently.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a cross-sectional view of the dust collection fan portion showing the second embodiment of the present invention, and FIG. 7 is a conceptual diagram for explaining the positional relationship between the dust collection fan 14 and the inner wall 37 of the housing. FIG. 8 is an enlarged view for explaining the positional relationship of the guide portion 38.

  As can be seen in FIG. 6, the distance between the inner wall 37 a and the outer peripheral end of the dust collecting fan 14 gradually becomes closer to the front or rear from the air supply port 36. This state will be further described with reference to the conceptual diagram of FIG. In FIG. 7, in order to understand the positional relationship, a reference line 57 extending from the air flow port 36 to the opposite side through the center point 61 of the inner wall of the housing, and an auxiliary line that is orthogonal to the reference line 57 and passes through the center point 61. Line 58 is drawn. The center point 60 of the dust collecting fan 14 is offset with respect to the center point 61 of the inner wall of the housing.

  If the area defined by the reference line 57 and the auxiliary line 58 is defined as (I) (II) (III) (IV) as shown in FIG. 7, the air flow port 36 is formed over the areas (I) (II). Is done. The first discharge port 35a is formed in the region (III). The second discharge port 35b is formed in the region (IV). With such an arrangement, the inflow pressure to the air flow port 36 is increased, the flow velocity is increased, the flow rate can be increased, and the air flow can be efficiently introduced into the dust collecting adapter 10. However, the above relationship is influenced by other factors such as the vertical height of the air supply port and the discharge port.

  In the second embodiment, as a device for increasing the inflow pressure, a guide portion 38 that protrudes in the central direction of the centrifugal fan is formed adjacent to the downstream side of the air flow port 36. Details thereof will be described with reference to FIG. FIG. 8 is a partially enlarged view for explaining the positional relationship of the guide portion 38 of FIG.

  In FIG. 8, a dash-dot line reference line 39 is drawn to indicate the position of the cylindrical inner wall of the housing. As can be seen from a comparison between the reference line 39 and the protruding state of the guide portion 38, a guide portion 38 that protrudes the inner wall portion on the downstream side of the air flow port 36 by a distance B in the central direction of the centrifugal fan is formed. By configuring the guide portion 38 in this way, the airflow flowing in the direction of the arrow 55 collides with the guide portion 38, and most of the airflow is guided toward the airflow port 36. As a result, in this case, not only the flow rate to the air flow port 36 increases, but also the effect that the pressure of the blast becomes higher and the flow velocity becomes faster is obtained.

  As is clear from the above description, according to the present invention, it is possible to sufficiently secure the air flow rate of the air flow to the vicinity of the drilling hole, improve the dust collection efficiency of dust generated during the drilling operation, and perform drilling after the drilling operation. Since the performance of removing dust remaining in the hole has been improved, it is possible to improve the work site and the worker's environment.

  Further, according to the present invention, in a drilling tool having a dust collecting device provided with a suction port for sucking air together with dust and a blower outlet for blowing air, dust can be efficiently collected and blown using a single centrifugal fan. The effect is obtained.

  As mentioned above, although demonstrated based on embodiment which shows this invention, this invention is not limited to the above-mentioned form, A various change is possible within the range which does not deviate from the meaning.

  For example, in the present invention, a drilling tool using an electric motor has been described. However, the drive source is not limited to the electric motor, and may be used for a drilling tool using an internal combustion engine or compressed air. Further, the dust collection fan 14 and the cooling fan 17 may be integrated instead of separate. In that case, air from the discharge port of the dust collecting fan may be sent to the motor 18.

It is a side view of the drilling tool which shows embodiment of this invention, and shows a cross section only for a dust collection part and a motor part. It is a side view which shows the state at the time of use of the drilling tool which shows embodiment of this invention, and shows a cross section only for a dust collection part and a motor part. The figure for demonstrating the flow of the air in the dust collecting adapter 10 of the drilling tool of FIG. Sectional drawing of the AA part of FIG. The conceptual diagram for demonstrating the positional relationship of the airflow port 36 and the 1st and 2nd discharge ports 35a and 35b. Sectional drawing of the dust collection fan part which shows the 2nd Embodiment of this invention. The conceptual diagram for demonstrating the positional relationship of the dust collecting fan 14 and the inner wall 37 of a housing. The elements on larger scale for demonstrating the positional relationship of the guide part 38 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hammer drill body 2 Housing 3 Handle 4 Power switch 5 Power cord 6 Switching member 8 Work material 10 Dust collection adapter 10a Air outlet 10b Suction port 11 Dust passage 12 Dust collection case 13 Filter 14 Dust collection fan 15 Air passage 16 Tail cover 17 Cooling fan 18 Motor 19 Rotating shaft 20 Guide flow path
22 Housing (for dust collector) 26 Tip tool
26a Tip portion (of the tip tool) 26b Spiral portion (of the tip tool)
31 Slider 33 (Dust collector) housing
35a, 35b Discharge port 36 Air supply port 37 Inner wall 38 Guide part 39 Reference line 41 Lock mechanism 57 Reference line 58 Auxiliary line 60 Center point of dust collecting fan 61 Center point 63, 64, 65, 66 of inner wall of housing Dust fan distance

Claims (12)

A drive source, and a transmission drive unit that transmits the rotational force of the drive source to rotate the tip tool;
A drilling tool having a dust collector that collects dust generated from a work material drilled by the tip tool and blows air in the vicinity of the hole to be drilled,
Filter means for filtering the dust-mixed air, and a centrifugal fan that takes in the filtered air and sends it out in the circumferential direction,
The centrifugal fan is disposed in a housing in which a part of the taken-in air is sent to the dust collector for blowing and a discharge port for discharging the remaining air to the outside. And
A drilling tool characterized in that a distance of the airflow port to the discharge port in the front direction of rotation of the centrifugal fan is larger than a distance to the discharge port in the rear direction of rotation of the airflow port.   At least two discharge ports are provided, and the distance of the air flow port to the discharge port at the front of the centrifugal fan in the rotation direction is larger than the distance to the discharge port at the rear of the air flow port in the rotation direction. The drilling tool according to claim 1.   The drilling tool according to claim 2, wherein the driving source is an electric motor, and the centrifugal fan is provided on a rotating shaft of the electric motor.   The said discharge port is provided in the multiple places of the said housing, and all the said discharge ports are arrange | positioned within the rotation angle 180 degrees behind the rotation direction of the said air flow port. Drilling tool.   As the discharge port, a first discharge port and a second discharge port are provided, and the first discharge port is behind the air flow port in the rotation direction within a rotation angle of 90 degrees, and the second discharge port is the The drilling tool according to claim 4, wherein the drilling tool is disposed within a rotation angle of 90 to 180 degrees behind the airflow port in the rotation direction.   The housing has a substantially cylindrical inner wall surrounding the periphery of the centrifugal fan, and the distance between the outer peripheral end of the centrifugal fan and the inner wall in front of the rotation angle of the air flow port is the most near the air flow port. The distance between the outer peripheral end and the inner wall is made closer on the opposite side of the centrifugal fan shaft from the airflow port, and the distance gradually decreases from near the airflow port toward the opposite side. The drilling tool according to any one of claims 1 to 5, wherein   The housing has a substantially cylindrical inner wall surrounding the centrifugal fan, and the cylindrical central axis is offset toward the air supply port with respect to the rotational axis of the centrifugal fan. A drilling tool according to claim 6, wherein an inner wall is formed.   2. The drilling tool according to claim 1, wherein a guide portion that protrudes toward the center of the centrifugal fan is formed on the inner wall of the housing on the rear side of the air supply port.   2. The drilling tool according to claim 1, wherein the air supply port is provided at a rear side in a rotation direction of the centrifugal fan in a housing in a tip tool attachment direction. A drive source, and a transmission drive unit that transmits the rotational force of the drive source to rotate the tip tool;
A drilling tool having a dust collector that collects dust generated from a work material drilled by the tip tool and blows air in the vicinity of the hole to be drilled,
Filter means for filtering the dust-mixed air, and a centrifugal fan that takes in the filtered air and sends it out in the circumferential direction,
The centrifugal fan is disposed in a housing in which a part of the taken-in air is sent to the dust collector for blowing and a discharge port for discharging the remaining air to the outside. And
A drilling tool, wherein the pressure in front of the airflow port is increased in front of the airflow port in the rotational direction of the centrifugal fan. An electric motor, and a transmission drive unit that transmits the rotational force of the electric motor to rotate the tip tool;
A drilling tool having a dust collector that collects dust generated from a work material drilled by the tip tool and blows air in the vicinity of the hole to be drilled,
A filter means for filtering the dust-mixed dust-mixed air and a centrifugal fan that takes in the filtered air and sends it out in the circumferential direction are attached to the rotating shaft of the electric motor,
The centrifugal fan is disposed in a housing in which a part of the taken-in air is sent to the dust collector for blowing and a discharge port for discharging the remaining air to the outside. And
The housing has a substantially cylindrical inner wall surrounding the centrifugal fan,
The centrifugal tool is disposed in the housing such that the rotation axis thereof is shifted from the central axis of the inner wall to the side opposite to the air flow port.   The centrifugal fan is attached so that the distance between the centrifugal fan and the inner wall is the farthest near the air supply port, and gradually approaches the forward direction of the centrifugal fan from the air supply port. The drilling tool according to claim 11.

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