EP3978192A1

EP3978192A1 - Attachment for impact rotary tools and tool system

Info

Publication number: EP3978192A1
Application number: EP21199442.1A
Authority: EP
Inventors: Seiji Hashino; Hidenori Shimizu; Shinji Seko
Original assignee: Panasonic Corp
Current assignee: Panasonic Holdings Corp
Priority date: 2020-09-30
Filing date: 2021-09-28
Publication date: 2022-04-06
Also published as: CN114310799A; JP2022057466A; JP7457623B2; CN114310799B

Abstract

The problem to be overcome by the present disclosure is to provide an impact rotary tool attachment, which is easily removable from an impact rotary tool, and a tool system including such an impact rotary tool attachment. An impact rotary tool attachment (7; 7a; 7b; 7c) according to the present disclosure includes a coupling shaft (72) and an input shaft (71). The coupling shaft (72) is inserted into an insert hole (62) of an impact rotary tool (1), faces each of a plurality of spherical members, and receives rotational driving force transmitted from the impact rotary tool (1). The input shaft (71) receives the rotational driving force transmitted via the coupling shaft (72). The coupling shaft (72) includes an input part (721) and an output part (722). The input part (721) includes a thinner shaft portion (723). The thinner shaft portion (723) includes a part thinner than the output part (722) in at least a range from a position where the thinner shaft portion (723) faces the plurality of spherical members to a tip thereof located closer to the impact rotary tool (1).

Description

Technical Field

The present disclosure generally relates to an attachment for use in impact rotary tools (hereinafter referred to as "impact rotary tool attachment") and a tool system, and more particularly relates to an impact rotary tool attachment to which rotational driving force is transmitted from an impact rotary tool and a tool system including such an impact rotary tool attachment.

Background Art

JP 2015-020243 A discloses an impact rotary tool attachment for measuring a torque applied to a shaft portion that transmits the impact force produced by an impact rotary tool to a tip tool.

Summary of Invention

There has been a growing demand for an impact rotary tool attachment which is easily removable from an impact rotary tool.
In view of the foregoing background, it is therefore an object of the present disclosure to provide an impact rotary tool attachment, which is easily removable from an impact rotary tool, and a tool system including such an impact rotary tool attachment.
An impact rotary tool attachment according to an aspect of the present disclosure includes a coupling shaft and an input shaft. The coupling shaft is inserted into an insert hole of an impact rotary tool, faces each of a plurality of spherical members of the impact rotary tool, and receives rotational driving force transmitted from the impact rotary tool. The input shaft receives the rotational driving force transmitted from the impact rotary tool via the coupling shaft. The coupling shaft includes an input part and an output part. The input part receives the rotational driving force transmitted from the impact rotary tool along an axis of the coupling shaft. The output part extends along the axis from the input part and transmits the rotational driving force to the input shaft. The input part includes a thinner shaft portion. The thinner shaft portion includes a part thinner than the output part in at least a range from a position where the thinner shaft portion faces the plurality of spherical members to a tip thereof located closer to the impact rotary tool.
A tool system according to another aspect of the present disclosure includes: the impact rotary tool attachment described above; and an impact rotary tool to which the impact rotary tool attachment is attached.

Brief Description of Drawings

FIG. 1 is an exploded perspective view of a tool system according to a first embodiment;
FIG. 2 is a perspective view of the tool system;
FIG. 3 is a cross-sectional view illustrating a main part of an impact rotary tool that forms part of the tool system;
FIG. 4 is a cross-sectional view illustrating a main part of the tool system;
FIG. 5 is a perspective view illustrating a main part of a driving force conversion mechanism of an impact rotary tool attachment according to the first embodiment;
FIG. 6 is a front view of a coupling shaft of the impact rotary tool attachment;
FIG. 7 is a front view of a coupling shaft of an impact rotary tool attachment according to a variation;
FIG. 8 is an exploded perspective view of a tool system according to a second embodiment;
FIG. 9 is a cross-sectional view illustrating a main part of the tool system;
FIG. 10 is a side view illustrating a main part of a driving force conversion mechanism of an impact rotary tool attachment according to the second embodiment;
FIG. 11A is a schematic representation illustrating an implementation of a tool system according to a third embodiment;
FIG. 11B is a schematic representation illustrating another implementation of a tool system according to a third embodiment; and
FIG. 12 is a schematic representation of a tool system according to a variation of the third embodiment.

Description of Embodiments

Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. In the following description, any constituent element, having the same function and forming part of multiple embodiments, will be designated by the same reference numeral and a redundant description thereof will be omitted herein. Note that the embodiment to be described below is only an exemplary one of various embodiments of the present disclosure and should not be construed as limiting. Rather, the exemplary embodiment may be readily modified in various manners depending on a design choice or any other factor without departing from the scope of the present disclosure. The drawings to be referred to in the following description of embodiments are all schematic representations. That is to say, the ratio of the dimensions (including thicknesses) of respective constituent elements illustrated on the drawings does not always reflect their actual dimensional ratio. Note that the arrows indicating respective directions on the drawings are only examples and should not be construed as defining the directions in which the tool system 100 is supposed to be used. Furthermore, those arrows indicating the respective directions are shown on the drawings only for the sake of description and are insubstantial ones.
As used herein, if one direction is "perpendicular to" another direction, this expression means that these two directions are substantially perpendicular to each other. That is to say, these two directions may naturally form an angle of exactly 90 degrees between themselves but may also form an angle within 90 ± several degrees (e.g., 90 ± less than 10 degrees) between themselves.

(First embodiment)

(1) Overview

First, an overview of a tool system 100 according to a first embodiment will be described with reference to FIGS. 1-4.
As shown in FIG. 1, a tool system 100 according to the first embodiment includes an impact rotary tool 1 and an impact rotary tool attachment 7 (hereinafter referred to as an "attachment 7"). As shown in FIG. 2, the attachment 7 is attached to, and used integrally with, the impact rotary tool 1.
The impact rotary tool 1 according to this embodiment operates with motive power (such as electric power) supplied from a motive power source such as a battery pack 25. Specifically, as shown in FIG. 3, a motor 3 supplied with electric power from the battery pack 25 (see FIG. 1) turns to transmit rotational driving force to a first output shaft 450. If a tip tool such as a screwdriver bit is attached to the first output shaft 450, a member to be fastened such as a screw as the target of machining work may be attached to the impact rotary tool 1.
As shown in FIG. 3, the impact rotary tool 1 according to this embodiment includes a pair of (i.e., two) steel balls 65 (spherical members) that reduces the chances of a tip tool, attached to a first output shaft 450, coming off accidentally. The two steel balls 65 clamp, in a state where the tip tool is inserted into the insert hole 62, the tip tool in the upward/downward direction with the elastic force of a spring 66. The two steel balls' 65 clamping the tip tool reduces the chances of the tip tool, attached to the first output shaft 450, coming off accidentally.
The attachment 7 is attached to the impact rotary tool 1 as shown in FIG. 2. The attachment 7 includes a coupling shaft 72, to which rotational driving force is transmitted from the first output shaft 450 of the impact rotary tool 1, and an input shaft 71, to which the rotational driving force is transmitted from the impact rotary tool 1 via the coupling shaft 72 as shown in FIG. 4. The coupling shaft 72 according to this embodiment includes an input part 721 and an output part 722. The input part 721 receives the rotational driving force transmitted from the impact rotary tool 1 along an axis of the coupling shaft 72 (i.e., in the forward/backward direction). The output part 722 is a part extending forward in the forward/backward direction from the input part 721 and transmits the rotational driving force to the input shaft 71.
The input part 721 according to this embodiment includes a thinner shaft portion 723 including a part thinner than the output part 722 in at least a range from a position where the thinner shaft portion 723 faces the two steel balls 65 to a tip thereof located closer to the impact rotary tool 1. The thinner shaft portion 723 includes a part thinner than the output part 722, and therefore, reduces the chances of the input part 721 being pressed against the two steel balls 65. Thus, the attachment 7 according to this embodiment is easily removable from the impact rotary tool 1. In addition, this also reduces the chances of the input part 721 being dented by being pressed against the two steel balls 65.

(2) Details

Next, a detailed configuration for the tool system 100 according to this embodiment will be described with reference to FIGS. 1-6.
As shown in FIG. 1, the tool system 100 according to this embodiment includes the impact rotary tool 1 and the attachment 7. Also, as shown in FIG. 2, the attachment 7 is fixed to the impact rotary tool 1 by an attachment mechanism 8 (see FIG. 4) of the attachment 7 at a tip portion 211 (see FIG. 1) of the impact rotary tool 1.

(2.1) Configuration for impact rotary tool

First, a configuration for the impact rotary tool 1 of the tool system 100 according to this embodiment will be described with reference to FIGS. 1-3. In the following description, the direction in which a drive shaft 41 (see FIG. 3) to be described later and the first output shaft 450 are arranged side by side is hereinafter defined as a forward/backward direction with the first output shaft 450 supposed to be located forward of the drive shaft 41 (i.e., with the drive shaft 41 supposed to be located backward of the first output shaft 450). In addition, in the following description, the direction in which a barrel 21and a grip portion 22 to be described later are arranged one on top of the other will be hereinafter defined as an upward/downward direction with the barrel 21 supposed to be located upward of the grip portion 22 (i.e., with the grip portion 22 supposed to be location downward of the barrel 21).
As shown in FIGS. 1 and 2, the impact rotary tool 1 according to this embodiment is used in the tool system 100. A rechargeable battery pack 25 is attached removably to the impact rotary tool 1. The impact rotary tool 1 according to this embodiment operates by being powered by the battery pack 25. That is to say, the battery pack 25 is a power supply that supplies a current for driving the motor 3 (see FIG. 3). In this embodiment, the battery pack 25 is not a constituent element of the impact rotary tool 1. However, this is only an example and should not be construed as limiting. Alternatively, the impact rotary tool 1 may include the battery pack 25 as one of constituent elements thereof. The battery pack 25 includes an assembled battery formed by connecting a plurality of secondary batteries (such as lithium-ion batteries) in series and a case in which the assembled battery is housed.
As shown in FIG. 3, the impact rotary tool 1 includes a body 2, the motor 3, a transmission mechanism 4, and a trigger volume 24.
As shown in FIG. 3, the body 2 houses the motor 3 and a part of the transmission mechanism 4. The body 2 includes the barrel 21, the grip portion 22, and a battery attachment portion 23 as shown in FIG. 2. The barrel 21 has the shape of a cylinder having an opening at the tip (front end) thereof and a closed bottom at the rear end thereof. The grip portion 22 protrudes downward from the barrel 21. The battery attachment portion 23 is configured such that the battery pack 25 is attachable to, and removable from, the battery attachment portion 23. In this embodiment, the battery attachment portion 23 is provided at the tip portion (i.e., at the bottom) of the grip portion 22. In other words, the barrel 21 and the battery attachment portion 23 are coupled together via the grip portion 22.
The trigger volume 24 protrudes from the grip portion 22. The trigger volume 24 is an operating member for accepting an operating command for controlling the rotation of the motor 3 (see FIG. 3). The ON/OFF states of the motor 3 may be switched by pulling the trigger volume 24. In addition, the rotational velocity of the motor 3 is adjustable by the manipulative variable indicating how deep the trigger volume 24 has been pulled. Specifically, the greater the manipulative variable is, the higher the rotational velocity of the motor 3 becomes.
The motor 3 shown in FIG. 3 may be a brushless motor, for example. The motor 3 includes a rotary shaft 31 and transforms the electric power supplied from the battery pack 25 (see FIG. 2) into the rotational driving force to be applied to the rotary shaft 31.
The transmission mechanism 4 shown in FIG. 3 is located forward of the motor 3 in the internal space of the barrel 21. The transmission mechanism 4 includes an impact mechanism 40 and a planetary gear mechanism 48. The impact mechanism 40 includes the drive shaft 41, a hammer 42, a return spring 43, an anvil 45, and two steel balls (rolling elements) 49. The rotational driving force of the rotary shaft 31 of the motor 3 is transmitted to the drive shaft 41 via the planetary gear mechanism 48. The drive shaft 41 is provided between the motor 3 and the first output shaft 450.
The hammer 42 moves with respect to the anvil 45 to apply rotational impact to the anvil 45 with the motive power supplied from the motor 3. The hammer 42 includes a hammer body 420 and two projections 425 (only one of which is shown in FIG. 3). The two projections 425 protrude from one surface, facing the first output shaft 450, of the hammer body 420. The hammer body 420 has a through hole 421, through which the drive shaft 41 is passed. In addition, the hammer body 420 has two groove portions 423 on an inner peripheral surface of the through hole 421. The drive shaft 41 has two groove portions 413 on an outer peripheral surface thereof. The two groove portions 413 are connected together. The two steel balls 49 are interposed between the two groove portions 423 and the two groove portions 413. These two groove portions 423, two groove portions 413, and two steel balls 49 together form a cam mechanism. While the two steel balls 49 are moving, the hammer 42 is not only movable along the axis of the drive shaft 41 with respect to the drive shaft 41 but also rotatable with respect to the drive shaft 41. As the hammer 42 moves along the axis of the drive shaft 41 toward, or away from, the anvil 45, the hammer 42 rotates with respect to the drive shaft 41.
The anvil 45 includes the first output shaft 450, two impacting portions 451, and a base portion 452. The base portion 452 has a disk shape when viewed in plan in the forward/backward direction. The center of the base portion 452 substantially agrees with the center axis of the drive shaft 41. The first output shaft 450 holds either a tip tool or a coupling shaft 72 (see FIG. 4) thereon. The first output shaft 450 has a cylindrical shape and protrudes forward from the base portion 452. The two impacting portions 451 protrude from the base portion 452 along the radius of the base portion 452. The anvil 45 faces the hammer body 420 along the axis of the drive shaft 41. Also, while the impact mechanism 40 is not performing the impacting operation, the hammer 42 and the anvil 45 rotate along with each other with the two projections 425 of the hammer 42 and the two impacting portions 451 of the anvil 45 kept in contact with each other in the direction in which the drive shaft 41 rotates. Thus, at this time, the drive shaft 41, the hammer 42, and the anvil 45 (first output shaft 450) rotate along with each other.
The return spring 43 is interposed between the hammer 42 and the planetary gear mechanism 48. The return spring 43 according to this embodiment is configured as a conical coil spring. The impact mechanism 40 further includes a plurality of (e.g., two in the example illustrated in FIG. 3) steel balls 50 and a ring 51, both of which are interposed between the hammer 42 and the return spring 43. This makes the hammer 42 rotatable with respect to the return spring 43. The hammer 42 receives, from the return spring 43, force directed toward the first output shaft 450 in the direction aligned with the axis of the drive shaft 41.
In the following description, the movement of the hammer 42 toward the anvil 45 along the axis of the drive shaft 41 will be hereinafter referred to as a "forward movement of the hammer 42." On the other hand, the movement of the hammer 42 away from the anvil 45 along the axis of the drive shaft 41 will be hereinafter referred to as a "backward movement of the hammer 42."
The impact mechanism 40 starts performing the impacting operation when the load torque becomes equal to or greater than a predetermined value. Specifically, as the load torque increases, the proportion of the component of force that causes the hammer 42 to move backward increases with respect to the force produced between the hammer 42 and the anvil 45. When the load torque becomes equal to or greater than a predetermined value, the hammer 42 starts moving backward while compressing the return spring 43. Then, as the hammer 42 moves backward, the hammer 42 rotates with the two projections 425 of the hammer 42 allowed to go over the two impacting portions 451 of the anvil 45. Thereafter, the hammer 42 is caused to start moving forward upon receiving the force of restitution from the return spring 43. Then, when the drive shaft 41 makes approximately a half turn, the two projections 425 of the hammer 42 collide against the side surfaces of the two impacting portions 451 of the anvil 45. In this impact mechanism 40, every time the drive shaft 41 makes approximately a half turn, the two projections 425 of the hammer 42 collide against the two impacting portions 451. That is to say, every time the drive shaft 41 makes approximately a half turn, the hammer 42 applies rotational impact to the anvil 45.
In this manner, in this impact mechanism 40, collision occurs repeatedly between the hammer 42 and the anvil 45. The torque produced by this collision allows fastening members such as screws, bolts, or nuts to be fastened more tightly than in a situation where no collision occurs between the hammer 42 and the anvil 45.
Such a transmission mechanism 4 is housed in the metallic hammer case 400. The hammer case 400 has a circular through hole 402, which is provided through a front surface 401 thereof and allows the first output shaft 450 to pass therethrough. In addition, the hammer case 400 also includes a protruding portion 403 protruding forward from a circumferential edge of the through hole 402. The protruding portion 403 has a cylindrical shape. The protruding portion 403 has a plurality of (e.g., two in the example illustrated in FIG. 3) recesses 404, which are provided on an outer peripheral surface thereof. As shown in FIG. 4, pawls 81 of the attachment 7 are engaged with the recesses 404.
The first output shaft 450 has an insert hole 62 and a fixing mechanism 63. Into the insert hole 62, a tip tool such as a screwdriver bit or the coupling shaft 72 (bar-shaped member) of the attachment 7 is attached. The insert hole 62 according to this embodiment has a regular hexagonal shape when viewed along the axis of the coupling shaft 72 (i.e., in the forward/backward direction). As used herein, the "regular hexagonal shape" refers to not only a regular hexagon, of which the six sides have exactly the same length and the six interior angles are exactly equal to each other, but also a shape which is similar to, and may be regarded as, a regular hexagon.
For example, if a screwdriver bit is attached to the first output shaft 450, the transmission mechanism 4 transmits the rotational driving force of the rotary shaft 31 of the motor 3 to the screwdriver bit via the first output shaft 450, thus causing the screwdriver bit to turn. Causing the screwdriver bit to turn while keeping in contact with a fastening member (such as a screw) enables machining work such as fastening or loosening the fastening member to be performed. The transmission mechanism 4 includes the impact mechanism 40. The impact rotary tool 1 according to this embodiment is an electric impact screwdriver that enables a screw to be fastened while making the impact mechanism 40 perform an impacting operation. The impacting operation applies impacting force to the fastening member, such as a screw, via the first output shaft 450.
Meanwhile, if the coupling shaft 72 of the attachment 7 is attached to the first output shaft 450 (see FIG. 4), the transmission mechanism 4 transmits the rotational driving force of the rotary shaft 31 of the motor 3 to the coupling shaft 72 via the first output shaft 450. This causes the coupling shaft 72 to turn. Causing the coupling shaft 72 to turn allows the coupling shaft 72 to transmit the rotational driving force to the input shaft 71 of the attachment 7. It will be described later in the "(2.2) Configuration for attachment" section how the attachment 7 operates after the rotational driving force has been transmitted to the input shaft 71.
The fixing mechanism 63 includes a plurality of (e.g., two in the example illustrated in FIG. 3) holes 64, a plurality of (e.g., two in the example illustrated in FIG. 3) steel balls 65 (spherical members), a spring 66, a bit holder 67, and another spring 68. The fixing mechanism 63 is a mechanism for holding a tip tool such as a screwdriver bit with respect to the impact rotary tool 1. The two holes 64 are respectively provided at upper and lower ends of the insert hole 62 so as to be located forward of the tip of the protruding portion 403 of the hammer case 400. Each of the two holes 64 is a hole with the shape of an ellipse, of which the major axis is aligned with the forward/backward direction. The two steel balls 65 are respectively fitted into the two holes 64. The bit holder 67 has the shape of a cylinder, of which the front and rear surfaces are open, and covers the outer periphery of the first output shaft 450 at the tip of the first output shaft 450. The spring 66 is a helical spring covering the outer periphery of the first output shaft 450 between the first output shaft 450 and bit holder 67. When a tip tool is inserted into the insert hole 62, the tip tool pushes the two steel balls 65 obliquely upward and obliquely downward, respectively, by overcoming the elastic force of the spring 66. In a state where the tip tool is inserted into the insert hole 62, the two steel balls 65 are allowed to clamp the tip tool between themselves by the elastic force of the spring 66. If the tip tool is provided with a groove to receive the steel balls 65, then the steel balls 65 are fitted into the groove of the tip tool, thereby fixing the tip tool with respect to the impact rotary tool 1. The spring 68 is a helical spring which is located forward of the spring 66 and covers the outer periphery of the first output shaft 450 between the first output shaft 450 and the bit holder 67. Causing the bit holder 67 to move forward against the elastic force applied by the spring 68 leaves a space between the bit holder 67 and the spring 66 in the upward/downward direction between the two holes 64. The steel balls 65 fitted into the groove of the tip tool may be disengaged from the groove by making the two steel balls 65 move into the space.
As described above, the two (i.e., a pair of) steel balls 65 are movable in both the forward/backward direction and the upward/downward direction. In a state where the tip tool does not push the two steel balls 65 obliquely upward and obliquely downward, respectively, by overcoming the elastic force of the spring 66 (i.e., in a default state), the gap distance as measured in the upward/downward direction between the two steel balls 65 is a minimum gap distance W1. Meanwhile, the coupling shaft 72 of the attachment 7 according to this embodiment has no groove into which the steel balls 65 are fitted.
As can be seen, the first output shaft 450 is a constituent element for holding a tip tool such as a screwdriver bit. Note that in this embodiment, the tip tool is not one of the constituent elements of the impact rotary tool 1.

(2.2) Configuration for attachment

Next, a configuration for the attachment 7 of the tool system 100 according to this embodiment will be described with reference to FIGS. 4-6.
As shown in FIG. 4, the attachment 7 according to this embodiment includes a housing 70, the input shaft 71, the coupling shaft 72, a second output shaft 73, the attachment mechanism 8, and the driving force conversion mechanism 9.
The housing 70 houses the input shaft 71, the coupling shaft 72, a part of the second output shaft 73, a part of the attachment mechanism 8, and the driving force conversion mechanism 9.
The coupling shaft 72 couples the first output shaft 450 to the input shaft 71 and drives the first output shaft 450 and the input shaft 71 integrally with each other. The coupling shaft 72 transmits the rotational driving force of the first output shaft 450 from the first output shaft 450 to the input shaft 71.
In addition, the coupling shaft 72 further includes an input part 721 and an output part 722.
The input part 721 is located at one end along the axis of the coupling shaft 72 (i.e., in the forward/backward direction), to which the rotational driving force is transmitted from the impact rotary tool 1. In addition, the input part 721 is a part to be inserted into the insert hole 62 of the impact rotary tool 1. The input part 721 has a regular hexagonal prism shape as a whole and has a shape corresponding to that of the insert hole 62 of the impact rotary tool 1. Specifically, the cross-sectional shape of the input part 721 is the same as the shape of the insert hole 62. For example, if the insert hole 62 has a regular hexagonal shape as in this embodiment, then the input part 721 has a regular hexagonal cross-sectional shape and the insert hole 62 also has a regular hexagonal shape. As used herein, the "regular hexagonal prism shape" refers to not only a regular hexagonal prism, of which the bottom and top surfaces both have a regular hexagonal shape, in which six sides, each connecting a pair of associated vertices of the bottom and top surfaces, have an equal length, and in which those six sides, the bottom surface, and the top surface intersect with each other at right angles, but also a shape which is similar to, and may be regarded as, a regular hexagonal prism as well.
The input part 721 has a thinner shaft portion 723. The thinner shaft portion 723 includes a part thinner than the output part 722 in at least a range from a position where the thinner shaft portion 723 faces the two steel balls 65 to a tip thereof located closer to the impact rotary tool 1. As shown in FIG. 4, the thinner shaft portion 723 includes a part thinner than the output part 722 in a direction in which the thinner shaft portion 723 faces the two steel balls 65. This allows the attachment 7 according to this embodiment to be inserted into, and removed from, the impact rotary tool 1 more easily.
The thinner shaft portion 723 according to this embodiment is provided with a plurality of recesses 724 (see FIG. 5) in the range from the position where the thinner shaft portion 723 faces the two steel balls 65 to the tip thereof located closer to the impact rotary tool 1, and therefore, is thinner than the output part 722. In the example illustrated in FIGS. 4 and 6, when measured in a direction (upward/downward direction) perpendicular to the axis of the coupling shaft 72 (forward/backward direction), the width W2 between the two (i.e., the pair of) recesses 724 of the thinner shaft portion 723 is smaller than the width W3 of the output part 722. On the other hand, the rest of the input part 721 according to this embodiment, other than the thinner shaft portion 723, has the same shape and the same dimension as the output part 722. That is to say, when measured in the upward/downward direction, the width of the non-thinner shaft portion 723 of the input part 721 is equal to the width W3 of the output part 722.
Furthermore, the width W2 between the pair of recesses 724 according to this embodiment is equal to or less than the minimum gap distance W1 (see FIG. 3) between the pair of steel balls 65. In other words, when measured in the upward/downward direction, the width W2 of the part, facing the pair of steel balls 65, of the thinner shaft portion 723 is equal to or less than the minimum gap distance W1 between the pair of steel balls 65. Stated otherwise, it can also be said that the width W2 is the width of the thinner shaft portion 723 as measured in the direction in which the thinner shaft portion 723 faces the steel balls 65. Since the width W2 between the pair of recesses 724 is equal to or less than the minimum gap distance W1 between the pair of steel balls 65, the thinner shaft portion 723 according to this embodiment may reduce the pressing force applied by the steel balls 65.
As shown in FIG. 6, the thinner shaft portion 723 is provided with the recess 724 in each of the six side surfaces of its regular hexagonal prism. In other words, the thinner shaft portion 723 according to this embodiment has six recesses 724.
As shown in FIG. 6, each of the six recesses 724 has the shape of an arc, corresponding to the shape of the steel balls 65, when viewed in plan along the axis of the coupling shaft 72.
In addition, the thinner shaft portion 723 also has six raised portions 725, each of which is provided between an associated pair of adjacent recesses 724 out of the six recesses 724. In this example, each of the six raised portions 725 according to this embodiment corresponds to an associated one of the six vertices of the regular hexagon. When the input part 721 is inserted into the insert hole 62 of the impact rotary tool 1, the six raised portions 725 are in contact with the inner walls 621 of the insert hole 62. Since the raised portions 725 and the inner walls 621 of the insert hole 62 are in contact with each other, the rotational driving force is transmitted from the impact rotary tool 1 to the thinner shaft portion 723 as well.
As shown in FIG. 4, the output part 722 is a part extended forward in the forward/backward direction from the input part 721 and transmits the rotational driving force to the input shaft 71. The output part 722 according to this embodiment has a regular hexagonal shape corresponding to the shape of the insert hole 711 of the input shaft 71. Specifically, the cross-sectional shape of the output part 722 is the same as the shape of the insert hole 711. For example, if the output part 722 has a regular hexagonal prism shape as in this embodiment, then the output part 722 has a regular hexagonal cross-sectional shape and the insert hole 711 also has a regular hexagonal shape. The output part 722 according to this embodiment is press-fitted into the insert hole 711 of the input shaft 71. In other words, the coupling shaft 72 and the input shaft 71 according to this embodiment are formed integrally with each other and the coupling shaft 72 and the input shaft 71 are driven integrally with each other.
The attachment mechanism 8 is used to fix the housing 70 of the attachment 7 to the tip portion 211 of the impact rotary tool 1. The attachment mechanism 8 includes a plurality of (e.g., two in the example illustrated in FIG. 4) pawls 81 and a plurality of (e.g., two in the example illustrated in FIG. 4) springs 82.
Each of the pawls 81 includes a surface portion 811, a base portion 812, a shaft portion 813, a protruding portion 814, and a hook 816. The surface portion 811 is exposed on the housing 70 and has a rectangular shape when viewed in plan in the upward/downward direction. The base portion 812 protrudes toward the coupling shaft 72 under a rear part of the surface portion 811. The shaft portion 813 is a shaft extending in the rightward/leftward direction and provided for a tip 815, facing the coupling shaft 72, of the base portion 812. The shaft portion 813 is rotatably supported by a bearing 707 provided for the inner walls 701 of the housing 70. The protruding portion 814 protrudes from the back surface (inside surface) of the surface portion 811 toward the coupling shaft 72 and has a cylindrical shape. A helical spring 82 is wound around the outer periphery of the protruding portion 814. The spring 82 is arranged between the surface portion 811 and the inner walls 701 while housing the protruding portion 814 inside. The hook 816 protrudes backward from a rear end, facing the coupling shaft 72, of the base portion 812 and has the shape of a hook. A tip 818 (i.e., either a lower end or an upper end) of the hook 86 is engaged with the recess 404 of the hammer case 400, thus allowing the pawl 81 to fix the housing 70 of the attachment 7 to the impact rotary tool 1. The pawl 81 presses the recess 404 of the hammer case 400 toward the coupling shaft 72 with the elastic force applied by the spring 82.
The pawl 81 further includes an operating member 817. When the user of the impact rotary tool 1 applies force to the operating member 817 such that the force is transmitted toward the coupling shaft 72 against the elastic force applied by the spring 82, the hook 816 moves outward (i.e., away from the coupling shaft 72) around the shaft portion 813. In other words, when the user applies force to the operating member 817 against the elastic force applied by the spring 82, the tip 818 of the hook 816 may be brought out of engagement with the recess 404. That is to say, the pawl 81 is displaced by the elastic force applied by the spring 82 from a position where the pawl 81 is engaged with the recess 404 to a position where the pawl 81 is disengaged from the recess 404, and vice versa.
The input shaft 71 is arranged forward of the coupling shaft 72 such that the center axis of the input shaft 71 substantially agrees with the center axis of the coupling shaft 72. As described above, the input shaft 71 and the coupling shaft 72 are driven integrally with each other and the rotational driving force is transmitted to the input shaft 71 from the coupling shaft 72. The input shaft 71 is supported rotatably by a bearing 702 fixed on two inner walls 701 of the housing 70.
The driving force conversion mechanism 9 includes a first gear 91 provided on the outer periphery of the input shaft 71 and a second gear 92 provided on the outer periphery of the second output shaft 73. The first gear 91 and the input shaft 71 are driven integrally with each other. In addition, the second gear 92 and the second output shaft 73 are also driven integrally with each other. In addition, as shown in FIG. 5, the driving force conversion mechanism 9 further includes a third gear 93 located in the upward/downward direction between the first gear 91 and the second gear 92. The third gear 93 has a shaft 931 parallel to the input shaft 71 and the second output shaft 73. Each of the first gear 91, the second gear 92, and the third gear 93 is a spur gear with a plurality of teeth protruding in the radial direction. The first gear 91 and the third gear 93 mesh with each other. The third gear 93 and the second gear 92 mesh with each other.
The driving force conversion mechanism 9 further includes a pair of supporting plates 94. The pair of supporting plates 94 is located forward of the tip (front end) of the coupling shaft 72. The pair of supporting plates 94 are provided at an interval larger than the axial length of any of the first gear 91, the second gear 92, or the third gear 93 as measured in the forward/backward direction. The pair of supporting plates 94 rotatably supports the input shaft 71, the shaft 931 of the third gear 93, and the second output shaft 73.
When the rotational driving force is transmitted to the input shaft 71, the input shaft 71 and the first gear 91 turn integrally with each other. The first gear 91 and the third gear 93 mesh with each other. Thus, as the first gear 91 turns, the rotational driving force is transmitted from the first gear 91 to the third gear 93. The third gear 93, to which the rotational driving force has been transmitted from the first gear 91, turns in the opposite direction from the direction in which the first gear 91 turns. In addition, the third gear 93 and the second gear 92 also mesh with each other. Thus, as the third gear 93 turns, the rotational driving force is transmitted from the third gear 93 to the second gear 92. The second gear 92, to which the rotational driving force has been transmitted from the third gear 93, turns in the opposite direction from the direction in which the third gear 93 turns. That is to say, the second gear 92 turns in the same direction as the first gear 91. The third gear 93 and the second output shaft 73 are driven integrally with each other. Thus, the rotational driving force transmitted to the third gear 93 is transmitted to the second output shaft 73.
As described above, the driving force conversion mechanism 9 according to this embodiment transmits the rotational driving force indirectly from the first gear 91 to the second gear 92 via the third gear 93. The rotational axis Ax1 of the input shaft 71 and the rotational axis Ax2 of the second output shaft 73 are generally parallel to each other. That is to say, the driving force conversion mechanism 9 according to this embodiment translates the rotational axis Ax0 of the rotation produced by the rotational driving force when transmitting the rotational driving force from the input shaft 71 to the second output shaft 73. Specifically, the driving force conversion mechanism 9 according to this embodiment translates the rotational axis Ax0 of the rotation produced by the rotational driving force from the rotational axis Ax1 of the input shaft 71 to the rotational axis Ax2 of the second output shaft 73.
The second output shaft 73 is supported rotatably by a bearing 703 fixed on the housing 70 as shown in FIG. 4. The second output shaft 73 is generally parallel to the input shaft 71 and arranged beside the input shaft 71 in the upward/downward direction and the rightward/leftward direction (i.e., directions perpendicular to the direction aligned with the input shaft 71). The second output shaft 73 has an insert hole 731 and a fixing mechanism 732. A tip tool such as a screwdriver bit is attached into the insert hole 731. Suppose a screwdriver bit is attached to the second output shaft 73. In that case, as the second output shaft 73 rotates, the screwdriver bit also rotates along with the second output shaft 73. Causing the screwdriver bit to rotate with the screwdriver bit kept in contact with a fastening member (such as a screw) allows a type of machining work such as fastening or loosening the fastening member to be done.
The fixing mechanism 732 includes a plurality of (e.g., two in the example illustrated in FIG. 4) holes 733, a plurality of (e.g., two in the example illustrated in FIG. 3) steel balls 734, a spring 735, a bit holder 736, and another spring 737. The two holes 733 are respectively provided at upper and lower ends of the insert hole 731 so as to be located forward of the tip of the housing 70. Each of the two holes 733 is a hole with the shape of an ellipse, of which the major axis is aligned with the forward/backward direction. The two steel balls 734 are respectively fitted into the two holes 733. The bit holder 736 has the shape of a cylinder, of which the front and rear surfaces are open, and covers the outer periphery of the second output shaft 73 in a region forward of the tip of the housing 70. The spring 735 is a helical spring covering the outer periphery of the second output shaft 73 between the second output shaft 73 and the bit holder 736. When a tip tool is inserted into the insert hole 731, the tip tool pushes the two steel balls 734 obliquely upward and obliquely downward, respectively, by overcoming the elastic force of the spring 735. In a state where the tip tool is inserted into the insert hole 731, the two steel balls 734 are allowed to clamp the tip tool between themselves in the upward/downward direction by the elastic force of the spring 735. If the tip tool is provided with a groove to receive the steel balls 734, then the steel balls 734 are fitted into the groove of the tip tool, thereby fixing the tip tool with respect to the attachment 7. The spring 737 is a helical spring which is located forward of the spring 735 and covers the outer periphery of the second output shaft 73 between the second output shaft 73 and the bit holder 736. Causing the bit holder 736 to move forward against the elastic force applied by the spring 737 leaves a space between the bit holder 736 and the spring 735 in the upward/downward direction between the two holes 733. The steel balls 734 fitted into the groove of the tip tool may be removed from the groove by making the two steel balls 734 move into the space.
The load torque of the second output shaft 73 is transmitted to the first output shaft 450 via the second gear 92, the third gear 93, the first gear 91, the input shaft 71, and the coupling shaft 72. As described above, when the load torque of the first output shaft 450 exceeds a predetermined level, the impact mechanism 40 applies impacting force in the rotational direction to the first output shaft 450. This impacting force in the rotational direction, as well as the rotational driving force, is transmitted to the second output shaft 73 via the coupling shaft 72, the input shaft 71, the first gear 91, the third gear 93, and the second gear 92. This allows the second output shaft 73 (of the attachment 7) to apply a greater fastening torque to the workpiece such as a fastening member.

(3) Advantages

As described above, the tool system 100 according to this embodiment includes the impact rotary tool 1 and the attachment 7. The attachment 7 includes a coupling shaft 72 and an input shaft 71. The coupling shaft 72 is inserted into an insert hole 62, faces each of two steel balls 65 of the impact rotary tool 1, and receives rotational driving force transmitted from the impact rotary tool 1. The coupling shaft 72 includes an input part 721 and an output part 722. The input part 721 includes a part thinner than the output part 722 in at least a range from a position where the coupling shaft faces the two steel balls 65 to a tip thereof located closer to the impact rotary tool 1. Thus, a thinner shaft portion 723 is provided in at least a range from a position where the coupling shaft 72 faces the two steel balls 65 to a tip thereof located closer to the impact rotary tool 1, and therefore, is less likely to come into contact with the two steel balls 65, thus making it easier to remove the input part 721(coupling shaft 72) from the insert hole 62. Therefore, the attachment 7 according to this embodiment is easily removable from the impact rotary tool 1.
In addition, the thinner shaft portion 723 according to this embodiment is thinner than the output part 722 by being provided with the six recesses 724 in the range from the position where the thinner shaft portion 723 faces the two steel balls 65 to the tip thereof located closer to the impact rotary tool 1. Thus, the coupling shaft 72 with the thinner shaft portion 723 may be formed easily by subjecting a coupling shaft with no thinner shaft portion 723 to machining of forming the recesses 724.
Furthermore, each of the six recesses 724 according to this embodiment has the shape of an arc when viewed in plan along the axis of the coupling shaft 72. This allows the recesses 724 to have such a shape that makes the recesses 724 extend along the steel balls 65. Therefore, even if the recesses 724 come into contact with the steel balls 65, their area of contact increases, thus reducing the chances of their portion in contact with the steel balls 65 being dented.
Furthermore, the thinner shaft portion 723 according to this embodiment has six raised portions 725, each of which is provided between an associated pair of adjacent recesses 724 out of the six recesses 724, and each of the six raised portions 725 is in contact with an inner wall 621 of the insert hole 62. Bringing each of the six raised portions 725 into contact with the inner wall 621 of the insert hole 62 allows the rotational driving force to be transmitted from the impact rotary tool 1 to the thinner shaft portion 723 via the six raised portions 725.
Furthermore, an attachment 7 according to this embodiment further includes: a housing 70 that houses the coupling shaft 72 and the input shaft 71 at least partially; and an attachment mechanism 8 that attaches and fixes the housing 70 onto the tip portion 211 of the impact rotary tool 1. Providing the attachment 7 with the attachment mechanism 8 allows the attachment 7 to be fixed to the impact rotary tool 1. In addition, since the housing 70 is fixed to the tip portion 211 of the impact rotary tool 1, which is located relatively close to the attachment 7, vibrations of the attachment 7 with respect to the impact rotary tool 1 may be reduced.
Furthermore, a width W2 of the thinner shaft portion 723 according to this embodiment as measured in the upward/downward direction in a region where the thinner shaft portion 723 faces the pair of (two) steel balls 65 (spherical members) is equal to or less than a minimum gap distance W1 between the two steel balls 65 as measured in the upward/downward direction. This substantially prevents the two steel balls 65 from being pressed against the thinner shaft portion 723. This allows the attachment 7 to be easily attached to, and removed from, the impact rotary tool 1.
Furthermore, the output part 722 of the coupling shaft 72 according to this embodiment is press-fitted into the input shaft 71. This may reduce the chances of the coupling shaft 72 dropping or being lost when the attachment 7 is attached to, or removed from, the impact rotary tool 1, because the coupling shaft 72 and the input shaft 71 are integrated with each other.

(4) Variations

Next, variations of the first embodiment will be enumerated one after another. Note that any of the variations to be described below may be adopted as appropriate in combination with the first embodiment described above.
The driving force conversion mechanism 9 may be configured to not only translate the rotational axis Ax0 of the rotation produced by the rotational driving force but also change the angle defined by the rotational axis Ax0 and/or convert the rotational driving force into thrust driving force applied along the rotational axis Ax0.
Optionally, the driving force conversion mechanism 9 may include an additional gear, besides the third gear 93, as a member to form a path for transmitting the rotational driving force from the first gear 91 to the second gear 92. That is to say, the driving force conversion mechanism 9 may include four or more gears in order to transmit the rotational driving force from the input shaft 71 to the second output shaft 73.
The driving force conversion mechanism 9 does not have to include the third gear 93 but may transmit the rotational driving force directly from the first gear 91 to the second gear 92. In that case, the first gear 91 and the second gear 92 are arranged to mesh with each other. Note that if the rotational driving force is transmitted directly from the first gear 91 to the second gear 92, then the direction in which the first gear 91 (input shaft 71) turns becomes opposite from the direction in which the second gear 92 (second output shaft 73) turns.
The attachment mechanism 8 does not have to include the spring 82. Alternatively, the hook 816 may be brought into engagement with the recess 404 of the hammer case 400 so that the hook 816 is pressed against the recess 404 with the elastic force of the hook 816 itself, for example.
Optionally, any part other than the hammer case 400 (e.g., a part of the barrel 21 of the impact rotary tool 1) may be made of a metallic material such that the attachment mechanism 8 may be attached thereto.
The insert hole 62 does not have to have a regular hexagonal shape. Alternatively, the insert hole 62 may also have any other regular polygonal shape such as an equilateral triangular shape or a square shape. As used herein, the "regular polygonal shape" refers to not only a "regular polygon" in a strict sense, of which all sides have the same length and all interior angles are equal to each other, but also a shape which is similar to, and may be regarded as, a regular polygon. Still alternatively, the insert hole 62 may also have a circular or elliptical shape.
The input part 721 does not have to have the shape of a regular hexagonal prism. Alternatively, the input part 721 may also have the shape of any other regular polygonal prism such as an equilateral triangular prism or a square prism. As used herein, the "regular polygonal prism shape" refers to not only a "regular polygonal prism" in a strict sense, of which the bottom and upper surfaces are the same regular polygon, all sides, each connecting a pair of corresponding vertices of the bottom and upper surfaces, have the same length, and all sides, bottom surface, and upper surface intersect with each other at right angles, but also a shape which is similar to, and may be regarded as, a regular polygonal prism. Still alternatively, the input part 721 may also have a circular columnar shape or an elliptical columnar shape.
The thinner shaft portion 723 of the coupling shaft 72 does not have to have the recesses 724 and the raised portions 725. As shown in FIG. 7, a thinner shaft portion 723 according to a variation has no recesses 724 or raised portions 725. The thinner shaft portion 723 according to this variation has a regular hexagonal shape when viewed in plan along the axis of the coupling shaft 72 and has the shape of a regular hexagonal prism extending along the axis of the coupling shaft 72 toward the output part 722. As in the first embodiment described above, the width W2 of the thinner shaft portion 723 as measured in the upward/downward direction is smaller than the width W3 of the output part 722 as measured in the upward/downward direction.
Note that the thinner shaft portion 723 does not have to have the regular hexagonal prism shape but may also have any other regular polygonal prism shape or a circular or elliptical columnar shape. The thinner shaft portion 723 has any arbitrary shape as long as the width W2 thereof as measured in a direction in which the thinner shaft portion 723 faces the steel balls 65 is smaller than the width W3 of the output part 722 as measured in the same direction.
Likewise, the output part 722 does not have to have the regular hexagonal prism shape but may also have any other regular polygonal prism shape or a circular or elliptical columnar shape.
In the first embodiment described above, the impact rotary tool 1 is implemented as an impact screwdriver, for example. However, this is only an example and should not be construed as limiting. Alternatively, the impact rotary tool 1 may also be implemented as an impact wrench, for example.

(Second embodiment)

(1) Overview

A tool system 100 according to a second embodiment includes, as shown in FIG. 8, an attachment 7a for converting the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force to be transmitted to the input shaft 71 (see FIG. 9), which is a major difference from the tool system 100 according to the first embodiment (see FIG. 4). In the following description, any constituent element of this second embodiment, having the same function as a counterpart of the first embodiment described above, will be designated by the same reference numeral as that counterpart's, and description thereof will be omitted as appropriate herein.

(2) Details

As shown in FIG. 9, the attachment 7a according to this embodiment includes the housing 70, the input shaft 71, the coupling shaft 72, the second output shaft 73, the attachment mechanism 8, and a driving force conversion mechanism 9a.
The input shaft 71 according to this embodiment is rotatably supported by a bearing 704 fixed to the housing 70.
The second output shaft 73 according to this embodiment is positioned to cross the input shaft 71. Specifically, the input shaft 71 extends in the forward/backward direction, while the second output shaft 73 extends in the upward/downward direction. The second output shaft 73 is rotatably supported by bearings 705 and 706 fixed to the housing 70.
The driving force conversion mechanism 9a according to this embodiment includes a first gear 91a provided on the outer periphery of the input shaft 71 and a second gear 92 provided on the outer periphery of the second output shaft 73. The first gear 91a and the input shaft 71 are driven integrally with each other. The second gear 92a and the second output shaft 73 are driven integrally with each other.
The first gear 91a and the second gear 92a according to this embodiment are bevel gears, of which the orientations are different from each other by 90 degrees and which mesh with each other (see FIG. 10). For example, as the input shaft 71 and the first gear 91a turn clockwise around the rotational axis Ax1, the second output shaft 73 and the second gear 92a turn clockwise around the rotational axis Ax3. The rotational axis Ax1 and the rotational axis Ax3 extend in two directions that intersect with each other at right angles.
As can be seen from the foregoing description, the driving force conversion mechanism 9a according to this embodiment changes the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force when transmitting the rotational driving force from the input shaft 71 to the second output shaft 73. Specifically, the driving force conversion mechanism 9a according to this embodiment changes the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force from the angle defined by the rotational axis Ax1 of the input shaft 71 into the angle defined by the rotational axis Ax3 of the second output shaft 73. As used herein, the angle defined by the rotational axis Ax0 refers to an angle defined by the rotational axis Ax0 with respect to a certain reference axis. In this embodiment, the rotational axis Ax1 of the input shaft 71 is used as the reference axis.

(3) Advantages

The driving force conversion mechanism 9a according to this embodiment includes: the first gear 91a provided for the input shaft 71; and the second gear 92a provided for the second output shaft 73. The driving force conversion mechanism 9a transmits the rotational driving force from the first gear 91a to the second gear 92a directly, thereby transmitting the rotational driving force to the second output shaft 73 that intersects with the input shaft 71. That is to say, the driving force conversion mechanism 9a according to this embodiment changes the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force transmitted to the input shaft 71. This allows, even when the workpiece such as a fastening member forms such an angle that makes it difficult to apply force thereto, a great fastening torque to be obtained with little pressing force, thus facilitating having the machining work done easily.

(4) Variations

Next, variations of the second embodiment will be enumerated one after another. Note that any of the variations to be described below may be adopted as appropriate in combination with the first embodiment or the variation thereof described above.
The driving force conversion mechanism 9a may also be configured to not only change the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force but also translate the rotational axis Ax0 and/or convert the rotational driving force into thrust driving force applied along the rotational axis Ax0.
In the driving force conversion mechanism 9a, the first gear 91a and the second gear 92a do not have to directly mesh with each other. Alternatively, another gear or any other suitable member may be arranged between the first gear 91a and the second gear 92a such that the rotational driving force is transmitted indirectly from the first gear 91a to the second gear 92a.

(Third embodiment)

(1) Overview

A tool system 100 according to a third embodiment includes an attachment 7b as shown in FIGS. 11A and 11B, which is a major difference from the tool system 100 according to the first embodiment. The attachment 7b according to this embodiment includes a driving force conversion mechanism 9b for converting the rotational driving force transmitted to the input shaft 71 into thrust driving force applied along the rotational axis Ax0. In the following description, any constituent element of this third embodiment, having the same function as a counterpart of the first embodiment described above, will be designated by the same reference numeral as that counterpart's, and description thereof will be omitted as appropriate herein.

(2) Details

As shown in FIGS. 11A and 11B, the attachment 7b according to this embodiment includes the housing 70, the input shaft 71, the coupling shaft 72, a second output shaft 73b, the attachment mechanism 8 (see, for example, FIG. 4), a driving force conversion mechanism 9b, a moving blade 74, and a fixed blade 75.
The second output shaft 73b according to this embodiment has a longitudinal axis extending in a direction aligned with the rotational axis Ax1 of the input shaft 71. The second output shaft 73b and the input shaft 71 are aligned with the rotational axis Ax0 of the rotation produced by the rotational driving force. The second output shaft 73b has the shape of a cylinder having an opening at the rear end thereof and a closed bottom at the front end (tip) thereof. The second output shaft 73b is arranged outside of the outer periphery of the input shaft 71 such that the inner periphery thereof covers the input shaft 71. In addition, the second output shaft 73b is supported by the housing 70 so as not to rotate.
The driving force conversion mechanism 9b according to this embodiment includes a first thread portion 95 and a second thread portion 96. The first thread portion 95 is provided on the outer periphery of the input shaft 71. The second thread portion 96 is provided on the inner periphery of the second output shaft 73b and screwed into the first thread portion 95. As the input shaft 71 rotates, the first thread portion 95 and the input shaft 71 rotate integrally with each other. As the first thread portion 95 rotates while being engaged with the second thread portion 96, thrust driving force is applied in the forward/backward direction to the second thread portion 96. That is to say, the driving force conversion mechanism 9b according to this embodiment converts the rotational driving force transmitted to the input shaft 71 into thrust driving force applied along the rotational axis Ax0 of the rotation produced by the rotational driving force and transmits the thrust driving force to the second thread portion 96 (the second output shaft 73b).
The direction of the thrust driving force transmitted in the forward/backward direction to the second thread portion 96 varies according to the rotational direction of the first thread portion 95. For example, if the first thread portion 95 rotates clockwise around the rotational axis Ax0, forward thrust driving force is transmitted to the second thread portion 96. When the forward thrust driving force is transmitted to the second thread portion 96, the second output shaft 73b moves forward within its movable range. On the other hand, if the first thread portion 95 rotates counterclockwise around the rotational axis Ax0, backward thrust driving force is transmitted to the second thread portion 96. When the backward thrust driving force is transmitted to the second thread portion 96, the second output shaft 73b moves backward within its movable range.
As can be seen from the foregoing description, the driving force conversion mechanism 9b according to this embodiment converts, when transmitting rotational driving force from the input shaft 71 to the second output shaft 73, the rotational driving force into thrust driving force applied along the rotational axis Ax0.
The moving blade 74 is a blade moving along with the second output shaft 73b. That is to say, as the second output shaft 73b moves forward, the moving blade 74 moves forward, too. As the second output shaft 73b moves backward, the moving blade 74 moves backward, too. The fixed blade 75 is a blade fixed to the housing 70. A position of the moving blade 74 where the workpiece T1 of cutting may be arranged between the moving blade 74 and the fixed blade 75 as shown in FIG. 11A will be hereinafter referred to as a "first position." On the other hand, a position of the moving blade 74 where the moving blade 74 and the fixed blade 75 overlap with each other in a direction perpendicular to the rotational axis Ax1 of the input shaft 71 as shown in FIG. 11B will be hereinafter referred to as a "second position." While the moving blade 74 is being displaced from the first position to the second position with the rotational driving force transmitted to the input shaft 71, the workpiece T1 of cutting is cut off by the moving blade 74 and the fixed blade 75.

(3) Advantage

The driving force conversion mechanism 9b according to this embodiment includes: a first thread portion 95 provided for the input shaft 71; and a second thread portion 96 provided for the second output shaft 73 and screwed into the first thread portion 95. The driving force conversion mechanism 9b causes, when the rotational driving force is transmitted from the input shaft 71 to the second output shaft 73, the second thread portion 96 and the second output shaft 73b to move along the rotational axis Ax0 of the rotation produced by the rotational driving force by turning the first thread portion 95 with the rotational driving force transmitted to the input shaft 71. That is to say, the driving force conversion mechanism 9b according to this embodiment converts the rotational driving force into the thrust driving force by causing the second thread portion 96 and the second output shaft 73b to move along the rotational axis Ax0 by turning the first thread portion 95. The attachment 7b according to this embodiment converts the rotational driving force to be transmitted to the input shaft 71 into thrust driving force applied along the rotational axis Ax0 of the rotational driving force, thus allowing the user to have a broader variety of machining work done.
In addition, in the tool system 100 according to this embodiment, the load torque of the input shaft 71 is transmitted to the first output shaft 450 via the coupling shaft 72. As described above, when the load torque of the first output shaft 450 exceeds a predetermined level, the impact mechanism 40 applies impacting force in the rotational direction to the first output shaft 450. This impacting force in the rotational direction, as well as the rotational driving force, is transmitted to the input shaft 71 via the coupling shaft 72, converted into thrust driving force by the driving force conversion mechanism 9b, and then transmitted to the second output shaft 73b. Thus, even when great force is required to cut off a workpiece T1, the workpiece T1 may also be cut off easily with the thrust driving force converted from the impacting force produced by the impact mechanism 40.

(4) Variations

Next, variations of the third embodiment will be enumerated one after another. Note that any of the variations to be described below may be adopted as appropriate in combination with the first embodiment or the variations thereof described above and/or the second embodiment or the variations thereof described above.
As shown in FIG. 12, the attachment 7c may include a moving portion 76 instead of the moving blade 74 according to the third embodiment and a fixed portion 77 instead of the fixed blade 75 according to the third embodiment. The attachment 7c may be used as a pressure bonding attachment for bonding a pair of workpieces together with pressure by clamping the pair of workpieces between the moving portion 76 and the fixed portion 77, for example.
The attachment 7c may function as a pressure bonding attachment by converting the rotational driving force to be transmitted to the input shaft 71 into thrust driving force applied along the rotational axis Ax0 of the rotational driving force. In addition, even if great force is required to bond a pair of workpieces together with pressure, the pair of workpieces may be easily pressure-bonded together with the thrust driving force converted from the impacting force produced by the impact mechanism 40.
The driving force conversion mechanism 9b may be configured to not only convert the rotational driving force into thrust driving force applied along the rotational axis Ax0 of the rotation produced by the rotational driving force but also translate the rotational axis Ax0 and/or change the angle defined by the rotational axis Ax0.

(Recapitulation)

As can be seen from the foregoing description, an impact rotary tool attachment (7; 7a; 7b; 7c) according to a first aspect includes a coupling shaft (72) and an input shaft (71). The coupling shaft (72) is inserted into an insert hole (62) of an impact rotary tool (1), faces each of a plurality of spherical members (steel balls 65) of the impact rotary tool (1), and receives rotational driving force transmitted from the impact rotary tool (1). The input shaft (71) receives the rotational driving force transmitted from the impact rotary tool (1) via the coupling shaft (72). The coupling shaft (72) includes an input part (721) and an output part (722). The input part (721) receives the rotational driving force transmitted from the impact rotary tool (1) along an axis of the coupling shaft (72). The output part (722) extends along the axis from the input part (721) and transmits the rotational driving force to the input shaft (71). The input part (721) includes a thinner shaft portion (723). The thinner shaft portion (723) includes a part thinner than the output part (722) in at least a range from a position where the thinner shaft portion (723) faces the plurality of spherical members (steel balls 65) to a tip thereof located closer to the impact rotary tool (1).
According to this aspect, the thinner shaft portion (723) of the input part (721) includes a part thinner than the output part (722) in a range from a position where the thinner shaft portion (723) faces the plurality of spherical members (steel balls 65) to a tip thereof located closer to the impact rotary tool (1), and therefore, is less likely to come into contact with the plurality of spherical members, thus making it easier to remove the coupling shaft (72) from the insert hole (62).
In an impact rotary tool attachment (7; 7a; 7b; 7c) according to a second aspect, which may be implemented in conjunction with the first aspect, the thinner shaft portion (723) is thinner than the output part (722) by being provided with a plurality of recesses (724) in the range from the position where the thinner shaft portion (723) faces the plurality of spherical members (65) to the tip thereof located closer to the impact rotary tool (1).
According to this aspect, the coupling shaft (72) with the thinner shaft portion (723) may be formed easily out of a bar-shaped member, of which the width is substantially uniform along its axis when measured perpendicularly to the axis of the coupling shaft (72).
In an impact rotary tool attachment (7; 7a; 7b; 7c) according to a third aspect, which may be implemented in conjunction with the second aspect, each of the plurality of recesses (724) has the shape of an arc when viewed in plan along the axis of the coupling shaft (72).
According to this aspect, the recesses (724) are allowed to extend along the spherical members (steel balls 65). Therefore, even if the recesses (724) come into contact with the steel balls (65), their area of contact increases, thus reducing the chances of their portion in contact with the steel balls 65 being dented.
In an impact rotary tool attachment (7; 7a; 7b; 7c) according to a fourth aspect, which may be implemented in conjunction with the second or third aspect, the thinner shaft portion (723) has a raised portion (725) provided between an associated pair of adjacent recesses (724) out of the plurality of recesses (724), and the raised portion (725) comes into contact with an inner wall (621) of the insert hole (62).
According to this aspect, the rotational driving force may also be transmitted from the impact rotary tool (1) to the thinner shaft portion (723) of the input part (721).
An impact rotary tool attachment (7; 7a; 7b; 7c) according to a fifth aspect, which may be implemented in conjunction with any one of the first to fourth aspects, further includes a housing (7) and an attachment mechanism (8). The housing (70) houses the coupling shaft (72) and the input shaft (71) at least partially. The attachment mechanism (8) attaches and fixes the housing (70) onto the impact rotary tool (1).
This aspect provides a configuration that allows the coupling shaft (72) to be removed easily from the insert hole (62) of the impact rotary tool (1) and yet allows the attachment (7; 7a; 7b; 7c) to be fixed with respect to the impact rotary tool (1).
In an impact rotary tool attachment (7; 7a; 7b; 7c) according to a sixth aspect, which may be implemented in conjunction with any one of the first to fifth aspects, the plurality of spherical members (steel balls 65) includes a pair of spherical members facing each other and movable in a direction perpendicular to the axis of the coupling shaft (72). A width (W2) of the thinner shaft portion (723) as measured in the direction perpendicular to the axis of the coupling shaft (72) in a region where the thinner shaft portion (723) faces the pair of spherical members is equal to or less than a minimum gap distance (W1) between the pair of spherical members (65) as measured in the direction perpendicular to the axis of the coupling shaft (72).
This aspect substantially prevents the pair of spherical members (steel balls 65) from being pressed against the input part (721).
In an impact rotary tool attachment (7; 7a; 7b; 7c) according to a seventh aspect, which may be implemented in conjunction with any one of the first to sixth aspects, the coupling shaft (72) is press-fitted into the input shaft (71).
This aspect may reduce the chances of the coupling shaft (72) dropping or being lost when the impact rotary tool attachment (7; 7a; 7b; 7c) is removed from the impact rotary tool (1).
Note that the constituent elements according to all of these aspects but the first aspect are not essential constituent elements for the attachment (7; 7a; 7b; 7c) but may be omitted as appropriate.
A tool system (100) according to an eighth aspect includes the impact rotary tool attachment (7; 7a; 7b; 7c) according to any one of the first to seventh aspects; and an impact rotary tool (1) to which the impact rotary tool attachment (7; 7a; 7b; 7c) is attached.
This aspect allows the impact rotary tool attachment (7; 7a; 7b; 7c) to be removed easily from the impact rotary tool (1).

Reference Signs List

1: Impact Rotary Tool
62: Insert Hole
621: Inner Wall
65: Steel Ball (Spherical Member)
7, 7a, 7b, 7c: Attachment (Impact Rotary Tool Attachment)
70: Housing
71: Input Shaft
72: Coupling Shaft
721: Input Part
722: Output Part
723: Thinner Shaft Portion
724: Recess
725: Raised Portion
100: Tool System

Claims

An impact rotary tool attachment (7; 7a; 7b; 7c) comprising:
a coupling shaft (72) configured to be inserted into an insert hole (62) of an impact rotary tool (1), face each of a plurality of spherical members (65) of the impact rotary tool (1), and receive rotational driving force transmitted from the impact rotary tool (1); and

an input shaft (71) configured to receive the rotational driving force transmitted from the impact rotary tool (1) via the coupling shaft (72),

the coupling shaft (72) including:
an input part (721) configured to receive the rotational driving force transmitted from the impact rotary tool (1) along an axis of the coupling shaft (72); and

an output part (722) extending along the axis from the input part (721) and configured to transmit the rotational driving force to the input shaft (71),

the input part (721) including a thinner shaft portion (723), the thinner shaft portion (723) including a part thinner than the output part (722) in at least a range from a position where the thinner shaft portion (723) faces the plurality of spherical members (65) to a tip thereof located closer to the impact rotary tool (1).
The impact rotary tool attachment (7; 7a; 7b; 7c) of claim 1, wherein
the thinner shaft portion (723) is thinner than the output part (722) by being provided with a plurality of recesses (724) in the range from the position where the thinner shaft portion (723) faces the plurality of spherical members (65) to the tip thereof located closer to the impact rotary tool (1).
The impact rotary tool attachment (7; 7a; 7b; 7c) of claim 2, wherein
each of the plurality of recesses (724) has a shape of an arc when viewed in plan along the axis of the coupling shaft (72).
The impact rotary tool attachment (7; 7a; 7b; 7c) of claim 2 or 3, wherein
the thinner shaft portion (723) has a raised portion (725) provided between an associated pair of adjacent recesses (724) out of the plurality of recesses (724), and

the raised portion (725) is configured to come into contact with an inner wall (621) of the insert hole (62).
The impact rotary tool attachment (7; 7a; 7b; 7c) of any one of claims 1 to 4, further comprising:
a housing (70) to house the coupling shaft (72) and the input shaft (71) at least partially; and

an attachment mechanism (8) configured to attach and fix the housing (70) onto the impact rotary tool (1).
The impact rotary tool attachment (7; 7a; 7b; 7c) of any one of claims 1 to 5, wherein
the plurality of spherical members (65) includes a pair of spherical members (65) facing each other and being movable in a direction perpendicular to the axis of the coupling shaft (72), and

a width (W2) of the thinner shaft portion (723) as measured in the direction perpendicular to the axis of the coupling shaft (72) in a region where the thinner shaft portion (723) faces the pair of spherical members (65) is equal to or less than a minimum gap distance (W1) between the pair of spherical members (65) as measured in the direction perpendicular to the axis of the coupling shaft (72).
The impact rotary tool attachment (7; 7a; 7b; 7c) of any one of claims 1 to 6, wherein the coupling shaft (72) is press-fitted into the input shaft (71).
A tool system (100) comprising:
the impact rotary tool attachment (7; 7a; 7b; 7c) of any one of claims 1 to 7; and

an impact rotary tool (1) to which the impact rotary tool attachment (7; 7a; 7b; 7c) is attached.