Patent Publication Number: US-11045939-B2

Title: Power tool

Description:
CROSS-REFERENCE 
     The present application claims priority to Japanese patent application serial number 2018-062172 filed on Mar. 28, 2018, the contents of which are incorporated fully herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a power tool, such as a so-called multi-tool, and more particularly to a power tool comprising a motor housing that houses a motor, a head housing held forward of the motor housing, and an output shaft protruding downward from the head housing. 
     BACKGROUND ART 
     WO 2012/045679 discloses a so-called “multi-tool” that is capable of performing a variety of types of work, such as cutting masonry boards (drywall) and wood, detaching plastic tiles, grinding wood materials, etc., by exchanging the tool accessory (e.g., blade, etc.) secured to an output shaft. 
     SUMMARY OF THE INVENTION 
     However, because a head housing (head cover) of the above-described known multi-tool is integrally made of metal (e.g., an aluminum alloy), the multi-tool is heavy and the multi-tool is not ergonomic and/or it is not easy to assemble. 
     Therefore, it is one non-limiting object of the present teachings to improve the ergonomics and/or simplify the assembly of a power tool comprising a motor housing, a head housing held forward of the motor housing, and an output shaft protruding downward from the head housing. 
     In a first aspect of the present teachings, a power tool comprises: a motor extending in a front-rear direction; a motor housing that houses the motor; a head housing held forward of the motor housing; and an output shaft protruding downward from the head housing. The head housing is made of a resin. 
     As a result, the power tool can be made more lightweight than the above-described known multi-tool, thereby improving ergonomics. 
     In a second aspect of the present teachings, a power tool comprises: a motor extending in a front-rear direction; a motor housing that houses the motor; a head housing held forward of the motor housing; and an output shaft protruding downward from the head housing. The head housing has a divided structure. 
     According to the above-described second aspect, for example, when assembling (mounting) the spindle unit in the inner part of the head housing, this assembly work can be performed more efficiently because the head housing is divided into the lower-head housing case and the upper-head housing cover. Accordingly, compared with the (non-divided) head housing of the above-described known multi-tool, the spindle unit can be more easily assembled (inserted) into the inner part of the head housing. 
     In addition, the divided structure optionally may comprise an upper half and a lower half, such that an upper-head housing case is joined to a lower-head housing cover. A dividing line (plane) between the upper and lower halves is located upward of an axis line (rotational axis) of the motor. 
     In such an embodiment, for example, if the power tool is a multi-tool, even if a torque acts on the lower-head housing case owing to the repetitive oscillating of the cutting tool about the axis of the output shaft, the lower-head housing case can be provided with sufficient stiffness to counteract this torque. 
     In addition or in the alternative, a rib may be formed on the upper-head housing cover and mates with the lower-head housing case. A tip side of the output shaft may be rotatably supported by the lower-head housing case via a bearing. An outer ring of the bearing may be held by the lower-head housing case. A tip of the rib preferably presses against the outer ring of the bearing. 
     In such an embodiment, rattling of the bearing in the axial direction can be prevented during operation of the power tool. 
     In a third aspect of the present teachings, a power tool comprises: a motor extending in a front-rear direction; a motor housing that houses the motor; a head housing held forward of the motor housing; and an output shaft protruding downward from the head housing. The head housing is integrally constituted. The motor housing has a two-halved structure in which half housings are joined. 
     In the above-described third aspect, the strength of the head housing can be increased over embodiments in which the head housing has a divided structure. In addition, because the motor housing is divided into two halves, the internal components (e.g., the motor, the centrifugal fan, the switch, etc.) can be joined to the housing part of the motor housing, thereby increasing the efficiency of this joining work. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a general oblique view of a multi-tool according to a first embodiment. 
         FIG. 2  is a side view of the multi-tool shown in  FIG. 1 . 
         FIG. 3  is an exploded view of the multi-tool shown in  FIG. 1 . 
         FIG. 4  is a side view of the multi-tool shown in  FIG. 3 . 
         FIG. 5  is a longitudinal-cross-sectional view of  FIG. 2 . 
         FIG. 6  is an enlarged view of the principal parts shown in  FIG. 5 . 
         FIG. 7  is a side view of the multi-tool according to a second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present teachings will be explained below, with reference to the drawings. 
     First Embodiment 
     A first embodiment of the present teachings will now be explained, with reference to  FIGS. 1-6 . It is noted that, in the following, examples are explained in which a “power tool” and an “output shaft” according to the present teachings are exemplified by a “multi-tool  1 ” and a “spindle  60 ,” respectively. In addition, in the following explanation, the terms “below”, “up”, “down”, “front”, “rear”, “left”, and “right” indicate the up, down, front, rear, left, and right directions noted in the drawings mentioned above. That is, the forward direction is the tip direction of the multi-tool  1 . This applies likewise in a second embodiment, which is described further below. 
     The multi-tool  1  principally comprises a motor housing  2 , a head housing (head cover)  7 , and a rear cover  8  (refer to  FIGS. 1-4 ). The motor housing  2 , the head housing  7 , and the rear cover  8  are described individually below. 
     First, the motor housing  2  will be explained. The motor housing  2  is integrally constituted (as one component) from a substantially tubular component made of resin. A motor  21  is joined to (mounted in) a housing part  20  (a tubular inner part) of the motor housing  2  such that the motor  21  extends in the front-rear direction (refer to  FIG. 5 ). A centrifugal fan  23  is joined to (mounted on) a front side of a rotary shaft  22  of the motor  21 . In addition, a first bearing  24  is assembled onto (mounted on) the rotary shaft  22  of the motor  21  on a front side of the centrifugal fan  23 . 
     A second bearing  25  is joined to (mounted on) the rotary shaft  22  of the motor  21  on the front side of the bearing  24 . The second bearing  25  is configured and mounted (refer to  FIG. 6 ) such that a second axis line b, which is the shaft axis of the second bearing  25 , is eccentric (displaced) with respect to (relative to) a first axis line a, which is the shaft axis (rotational axis) of the rotary shaft  22  of the motor  21  (refer to  FIG. 6 ). That is, the second bearing  25  is mounted such that it is eccentric with respect to the rotary shaft  22  of the motor  21 . 
     On the other side, a third bearing  26  is joined to (mounted on) a rear side of the rotary shaft  22  of the motor  21 . The first and third bearings  24 ,  26  constitute the bearings of the rotary shaft  22  of the motor  21 . Consequently, outer rings of both of the bearings  24 ,  26  are joined (affixed) to the housing part  20  of the motor housing  2 . Accordingly, the rotary shaft  22  of the motor  21  can be rotated smoothly. 
     In addition, a dish-shaped fan guide  27 , which surrounds the circumference of the centrifugal fan  23 , is joined, with the rotary shaft  22  of the motor  21  inserted therethrough, to the housing part  20  between the motor  21  and the centrifugal fan  23  of the motor housing  2 . The fan guide  27  makes it possible to increase the wind speed of outside air (cooling air) drawn in through air-suction ports  80  of the rear cover  8 , which are described below. In addition, air-exhaust ports  28  for exhausting the outside air drawn in through the air-suction ports  80  of the rear cover  8  are formed on the left and right (left- and right-side surfaces) of the motor housing  2 . 
     A rearward-extending projection  29  is formed on a rear part of the motor housing  2 . A switch  31  is joined to (mounted on) the front side of the projection  29  via a switch cover  30  (refer to  FIG. 5 ). In addition, a terminal block  33  is electrically connected to a power-supply cord  32  (for connecting to an external power supply) and is joined to (mounted on) a rear side of the projection  29 . In addition, a controller  34 , which drives the rotary shaft  22  of the motor  21 , is joined to (mounted on) the rear side of the projection  29 . In addition, a switch knob  35 , which is operable (slidable) by a finger of a user, is joined to (mounted on) an upper side of the motor housing  2 . 
     In addition, a switch lever  36 , which is interlocked with the operation (movement) of the switch knob  35  and actuates the switch  31 , is joined to (mounted on) the housing part  20  of the motor housing  2 . In addition, a speed-changing dial  37  for setting the rotational speed of the rotary shaft  22  of the motor  21  driven by the controller  34  is joined to (mounted on) a rear side of the projection  29 . It is noted that the motor  21 , the switch  31 , the terminal block  33 , and the speed-changing dial  37  are electrically connected to the controller  34  via lead wires (not shown). The motor housing  2  is thus configured. 
     Next, the head housing  7  will be explained. The head housing  7  principally comprises a lower-head housing case  4 , an upper-head housing cover  5 , and a spindle unit  6 . 
     The lower-head housing case  4  is integrally constituted (as one component) from a component made of a resin such that it has an inverted, substantially L-shaped housing part  40 . An inner diameter of an inner-circumferential surface  41  of the housing part  40  is set equal to or slightly larger than an outer diameter of an outer ring  63   b  of a bearing  63  of the spindle  60  of the spindle unit  6 , which is described below. Consequently, as described below, when the spindle unit  6  is joined to (mounted within) the housing part  40 , rattling of the spindle unit  6  in radial directions can be prevented. 
     A through hole  42  is formed in a lower side of the housing part  40 , and the spindle  60  of the spindle unit  6  is inserted through the through hole  42 . In addition, a joining part  43 , which projects from the inner-circumferential surface  41  toward the center of the through hole  42 , is formed on a lower side of the housing part  40 . A portion of the surface of the lower-head housing case  4  is covered by an elastomer  45 , such as a two-color molded elastomer  45 , to attenuate the transmission of vibration from the lower-head housing case  4  to the user&#39;s hand. The lower-head housing case  4  is thus configured. 
     In addition, the upper-head housing cover  5  is integrally constituted (as one component) from a component made of a resin such that, when the spindle unit  6  is joined to (mounted within) the housing part  40  of the lower-head housing case  4 , the upper-head housing cover  5  covers the spindle unit  6 . A substantially circular-cylinder-shaped rib  51  protrudes downward from a divided surface  50  of the upper-head housing cover  5 . 
     A base-end-side outer diameter of an outer-circumferential surface  52  of the rib  51  is set equal to or slightly larger than an upper-side inner diameter of the inner-circumferential surface  41  of the housing part  40  of the lower-head housing case  4 . Consequently, as described below, when the upper-head housing cover  5  is joined to (mounted on) the lower-head housing case  4 , the outer-circumferential surface  52  of the rib  51  of the upper-head housing cover  5  mates with the inner-circumferential surface  41  of the lower-head housing case  4 . Accordingly, rattling of the joined upper-head housing cover  5  in the radial directions can be reduced. 
     In addition, a recessed groove  54  is formed on (in) the divided (downward-facing) surface  50  of the upper-head housing cover  5 . A seal ring  55  is joined to (placed in) the recessed groove  54 . Consequently, as described below, after the upper-head housing cover  5  has been joined to the lower-head housing case  4 , the seal ring  55  prevents (blocks) grease (not shown), which is applied to the spindle unit  6  disposed within the housing part  40  of the lower-head housing case  4 , from leaking out between a divided (upward-facing) surface  44  of the lower-head housing case  4  and the divided surface  50  of the upper-head housing cover  5 , which face (adjoin) each other in the assembled state of the multi-tool  1 . 
     In addition, a portion of the surface of the upper-head housing cover  5  is covered by another elastomer  56 , such as a two-color molded elastomer  56 , to attenuate the transmission of vibration from the upper-head housing cover  5  to the user&#39;s hand. The upper-head housing cover  5  is thus configured. 
     In addition, the spindle unit  6  comprises: the spindle  60 ; a lever  61  having a base end joined (fastened) to an upper part of the spindle  60 ; the bearing  63 , which is joined to (mounted on) a lower-end side (tip side) of the spindle  60 ; and a bearing  64 , which is joined to (mounted on) an upper-end side (base-end side) of the spindle  60 . A clamping part  62 , which has opposing left and right pressing surfaces  62   a  and is substantially U-shaped in plan view, is formed on a tip of the lever  61 . 
     The above-described second bearing  25  of the rotary shaft  22  of the motor  21  is received (disposed) between the two pressing surfaces  62   a  of the clamping part  62  (refer to  FIG. 6 ). In addition, a mounting part  65  is joined (fastened) to a lower-end side of the spindle  60 . Protrusions  65   a  are formed along a circumferential direction (a circle) on a lower surface of the mounting part  65 . The spindle unit  6  is thus configured. 
     A procedure for assembling the above-described lower-head housing case  4 , the upper-head housing cover  5 , and the spindle unit  6  to form the head housing  7  will now be explained. First, the spindle unit  6  is joined to (mounted in) the housing part  40  of the lower-head housing case  4 . As a result, the spindle  60  of the spindle unit  6  protrudes downward from (through) the through hole  42  of the lower-head housing case  4 . 
     Next, the upper-head housing cover  5  is joined to (mounted on) the lower-head housing case  4 , which contains the spindle unit  6 . It is noted that, as can be seen in  FIG. 5 , a dividing line (plane) c, at (along) which the divided surface  44  of the lower-head housing case  4  and the divided surface  50  of the upper-head housing cover  5  meet, is located (extends) upward of the first axis line a of the rotary shaft  22  of the motor  21 . 
     In this joined state, a tip  53  of the rib  51  of the upper-head housing cover  5  downwardly presses against the outer ring  63   b  of the bearing  63  of the spindle unit  6  joined to the lower-head housing case  4 . Then, three screws  4   a  are fastened from the lower-head housing case  4  into the upper-head housing cover  5 . In this way, the head housing  7  is assembled. 
     Lastly, the rear cover  8  will be explained. The rear cover  8  is integrally constituted (as one component) from a bottomed, substantially tubular component made of a resin. Groove-shaped air-suction ports  80  for drawing in outside air are formed on the left and right (left and right side surfaces) on the rear side of the rear cover  8 . In addition, a through hole  81 , through which the power-supply cord  32  can pass, is formed on the rear side of the rear cover  8 . The rear cover  8  is thus configured. 
     Next, a procedure for assembling the motor housing  2 , the head housing  7 , and the rear cover  8  to form the multi-tool  1  will be explained. First, the rear cover  8  is joined to the motor housing  2  such that it covers the projection  29  of the motor housing  2 . Then, a screw  8   a  is fastened from the rear cover  8  into the projection  29  of the motor housing  2 . Thereafter, the head housing  7  is joined to the motor housing  2 . 
     Furthermore, four screws  4   b  are fastened from the head housing  7  into the motor housing  2  so that the head housing  7  is held (secured) forward of the motor housing  2 . Lastly, a cutting tool  66  having a blade  66   a  is interposed (sandwiched) between the mounting part  65  of the spindle  60  and an outer flange  67 , and then a flat-head screw  68  is tightened against the outer flange  67  into the mounting part  65  of the spindle  60 . Thereby, the cutting tool  66  is mounted on the mounting part  65  of the spindle  60 . 
     It is noted that a circle of cutout holes  66   b  is formed in the cutting tool  66  such that they correspond to the circle of protrusions  65   a  of the mounting part  65 . Consequently, when the cutting tool  66  is sandwiched (interleaved) between the mounting part  65  of the spindle  60  and the outer flange  67 , the protrusions  65   a  of the mounting part  65  are respectively inserted into cutout holes  66   b  formed in the cutting tool  66 . Accordingly, the cutting tool  66  can be mounted on the mounting part  65  of the spindle  60  with the blade  66   a  oriented frontward. In this way, the multi-tool  1  is assembled. 
     A representative method for operating the multi-tool  1  assembled as described above will now be explained. When the switch knob  35  is operated (manipulated, slid) by the user&#39;s finger, the motor  21  is driven by the controller  34 . Thereby, the rotary shaft  22  of the motor  21  rotates. Thereupon, because the second bearing  25  is eccentrically mounted with respect to (relative to) the rotary shaft  22  of the motor  21 , an outer-circumferential surface  25   c  of an outer ring  25   b  of the bearing  25  alternately presses (pushes) against the opposing left/right pressing surfaces  62   a  of the lever  61  of the spindle unit  6 . 
     This causes the lever  61  to repetitively oscillate about the pivot axis of the spindle  60 , whereby the cutting tool  66  also oscillates (pivots) repetitively about the pivot axis of the spindle  60 . Therefore, a workpiece, such as a masonry board (not shown), can be cut owing to the repetitive oscillating (pivoting movement) of the blade  66   a  of the cutting tool  66 . At this time, the centrifugal fan  23  also rotates together with the rotary shaft  22  of the motor  21 . Thereupon, outside air is drawn in from (through) the air-suction ports  80  of the rear cover  8  into the interior of the rear cover  8 , and this drawn-in outside air is subsequently exhausted from (through) the air-exhaust ports  28  of the motor housing  2 . 
     Because the inner part of the rear cover  8  and the housing part  20  of the motor housing  2  serve as a passageway for the outside air (i.e., because the outside air is delivered into the interior of the rear cover  8  and the housing part  20  of the motor housing  2 ), internal components, such as the controller  34 , the motor  21 , etc., are cooled. Accordingly, the motor  21  and the controller  34  can be prevented from overheating during operation. 
     The multi-tool  1  according to the first embodiment is configured as described above. According to this configuration, the head housing  7  is constituted from components made of resin. Consequently, as compared to the above-described known multi-tool, the multi-tool  1  of this aspect of the present teachings can be made more lightweight, thereby improving ergonomics (ease of use). 
     In addition, according to this configuration, the head housing  7  has a two-halved structure in which the lower-head housing case  4  and the upper-head housing cover  5  are joined together. Consequently, when the spindle unit  6  is joined to (mounted in) the inner part of the head housing  7 , this joining work can be carried out more efficiently, because the head housing  7  is divided into the lower-head housing case  4  and the upper-head housing cover  5 . Accordingly, compared with the head housing  7  of the above-described known multi-tool, the spindle unit  6  can be joined to (mounted in) the interior of the head housing  7  more easily and efficiently. 
     In addition, according to this configuration, the dividing line (plane) c between the divided surface  44  of the lower-head housing case  4  and the divided surface  50  of the upper-head housing cover  5  is located upward of the first axis line a of the rotary shaft  22  of the motor  21 . Consequently, even if a torque acts on the lower-head housing case  4  owing to the repetitive oscillating of the cutting tool  66  about the pivot axis of the spindle  60  of the spindle unit  6 , the lower-head housing case  4  can be provided with sufficient stiffness to counteract this torque. 
     In addition, according to this configuration, when the spindle unit  6  has been joined to (mounted in) the interior of the head housing  7  (the housing part  40  of the lower-head housing case  4 ), the tip  53  of the rib  51  of the upper-head housing cover  5  presses axially downward against the outer ring  63   b  of the bearing  63  of the spindle unit  6  joined to the lower-head housing case  4 . Consequently, in this joined state, rattling of the bearing  63  in the axial direction of the spindle  60  can be prevented. 
     Second Embodiment 
     Next, a second embodiment of the present teachings will be explained, with reference to  FIG. 7 . A multi-tool  101  according to the second embodiment differs from the multi-tool  1  according to the first embodiment in the structures of the motor housing  2  and the head housing  7 . It is noted that, in the explanation below, components of structural elements that are the same as or equivalent to components explained in the first embodiment are assigned the same numerals and symbols in the drawing, and redundant explanations thereof are omitted. 
     The multi-tool  101  principally comprises the motor housing  2  and the head housing  7  (refer to  FIG. 7 ). The motor housing  2  of the multi-tool  101  also serves as the rear cover  8  of the first embodiment and is composed of a bottomed, substantially tubular component made of resin. It is noted that the motor housing  2  of the multi-tool  101 , as can be seen in  FIG. 7 , has a two-halved structure in which upper and lower half housings  2   a ,  2   b  are joined together by screws (not shown). 
     In addition, the head housing  7  of the multi-tool  101  is integrally constituted by (as one component) the lower-head housing case  4  and the upper-head housing cover  5  of the first embodiment. It is noted that other structures of the multi-tool  101  are the same as those of the multi-tool  1 . 
     The multi-tool  101  according to the second embodiment of the present invention is configured as described above. According to this configuration, functions and effects the same or similar as those in the multi-tool  1  can be obtained. In addition, the head housing  7  of the multi-tool  101  is integrally constituted (i.e. as one integral unit without seams). Consequently, the strength of the head housing  7  can be increased as compared to a head housing having a divided structure. In addition, the motor housing  2  of the multi-tool  101  has a two-halved structure in which the upper and lower half housings  2   a ,  2   b  are joined by screws. Consequently, because the motor housing  2  of the second embodiment is divided into an upper half and a lower half, the components (e.g., the motor  21 , the centrifugal fan  23 , the switch  31 , etc.) can be joined to the housing part  20  of the motor housing  2  more easily and efficiently during assembly. 
     The details described above strictly relate to the embodiments of the present invention, and the present invention is not limited thereto. 
     In the embodiments, examples were explained in which the “power tool” is the “multi-tool  1 ,  101 .” However, embodiments of the present teachings are not limited thereto, and the “power tool” may be otherwise configured, e.g., as an “angle-type power tool.” 
     In addition, in the first embodiment, an example was explained in which the head housing  7  has an up-down two-halved structure. However, the first embodiment is not limited thereto, and the head housing  7  may have a front-rear two-halved structure or a left-right two-halved structure. Of course, the head housing  7  may be integrally constituted (as one component) from a component made of resin, as in the second embodiment. 
     In addition, in the first embodiment an example was explained in which the motor housing  2  is integrally constituted (as one component) from a substantially tubular component made of resin. However, the first embodiment is not limited thereto, and the motor housing  2  may be configured in halves (as two components constituting halves), such as longitudinal halves (left and right halves) or transverse halves (upper and lower halves), from substantially tubular components made of resin, as was described in the preceding paragraph and in the first embodiment. In such additional embodiments of the present teachings, screws fasten together the two components constituting the two halves. 
     In addition, in the second embodiment an example was explained in which the motor housing  2  of the multi-tool  101  has a two-halved structure in which the upper and lower half housings  2   a ,  2   b  are joined together by screws. However, the second embodiment is not limited thereto, and the motor housing  2  of the multi-tool  101  may have a two-halved structure in which left and right half housings  2   a ,  2   b  are joined by screws. 
     Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved power tools, such as angled power tools and more particularly, multi-tools. 
     Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings. 
     All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter. 
     EXPLANATION OF THE REFERENCE NUMBERS 
     
         
           1  Multi-tool (power tool, first embodiment) 
           2  Motor housing 
           2   a  Half housing 
           2   b  Half housing 
           4  Lower-head housing case 
           4   a  Screw 
           4   b  Screw 
           5  Upper-head housing cover 
           6  Spindle unit 
           7  Head housing 
           8  Rear cover 
           8   a  Screw 
           20  Housing part 
           21  Motor 
           22  Rotary shaft 
           23  Centrifugal fan 
           24  Bearing 
           25  Bearing 
           25   a  Inner ring 
           25   b  Outer ring 
           25   c  Outer-circumferential surface 
           26  Bearing 
           27  Fan guide 
           28  Air-exhaust port 
           29  Projection 
           30  Switch cover 
           31  Switch 
           32  Power-supply cord 
           33  Terminal block 
           34  Controller 
           35  Switch knob 
           36  Switch lever 
           37  Speed-changing dial 
           40  Housing part 
           41  Inner-circumferential surface 
           42  Through hole 
           43  Joining part 
           44  Divided surface 
           45  Elastomer 
           50  Divided surface 
           51  Rib 
           52  Outer-circumferential surface 
           53  Tip 
           54  Recessed groove 
           55  Seal ring 
           56  Elastomer 
           60  Spindle (output shaft) 
           61  Lever 
           62  Clamping part 
           62   a  Pressing surface 
           63  Bearing 
           63   a  Inner ring 
           63   b  Outer ring 
           64  Bearing 
           65  Mounting part 
           65   a  Protrusions 
           66  Cutting tool 
           66   a  Blade 
           66   b  Cutout hole 
           67  Outer flange 
           68  Flat-head screw 
           80  Air-suction port 
           81  Through hole 
           101  Multi-tool (power tool, second embodiment) 
         a First axis line (motor) 
         b Second axis line (bearing) 
         c Dividing line (plane)