Cover attachment

Abstract

To provide an improvement in a cover attachment that can be selectively attached to a protective cover of a grinder. [Solution] The cover attachment is attachable to a protective cover having an arc-shaped outer periphery, and includes: an arc-shaped first cover portion extending along the outer surface of the outer periphery of the protective cover; a flat second cover portion extending radially inward from the first cover portion; a first engagement member provided near a first end of the first cover portion; and a second engagement member provided near a second end of the first cover portion. The first engagement member is biased relative to the first cover portion in a first direction substantially parallel to a tangent to the first cover portion at the first end and configured to engage with the first end of the outer periphery of the protective cover. The second engagement member is biased relative to the first cover portion in a second direction substantially parallel to a tangent to the first cover portion at the second end and configured to engage with the second end of the outer periphery of the protective cover.

Description

[Technical Field]

[0001] The present disclosure relates to a cover attachment that can be attached to a protective cover of a grinder. [Background technology]

[0002] Grinders perform machining operations by rotating a disc-shaped tool bit removably attached to a spindle. During machining operations, a protective cover that partially covers the tool bit is attached to the grinder to prevent dust and sparks from flying. For example, during grinding and polishing of a workpiece, it is necessary to cover one of the two surfaces of the disc-shaped tool bit that faces the grinder body. Meanwhile, during cutting of a workpiece, it is necessary to cover both surfaces of the disc-shaped tool bit. To avoid the need to replace the entire protective cover depending on the machining operation, a wheel cover is known that includes a first cover suitable for grinding and polishing operations and a second cover that can be selectively attached to the first cover during cutting operations (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-153893 Summary of the Invention [Problem to be solved by the invention]

[0004] The first and second covers described above each have a semicircular shape that corresponds to approximately half of the bit. The first cover has an edge protection portion that covers the outer periphery of the bit. The second cover has an edge protection portion that is disposed along the outer surface of the edge protection portion of the first cover. The second cover is attached to the first cover with both circumferential ends of the edge protection portion of the second cover engaged with the edge protection portion of the first cover, but there is room for further improvement in stabilizing the attachment state between the first and second covers.

[0005] In view of the above, it is one non-limiting object of the present disclosure to provide an improvement relating to a cover attachment that is selectively attachable to a protective cover of a grinder. [Means for solving the problem]

[0006] According to one non-limiting aspect of the present disclosure, there is provided a cover attachment attachable to a protective cover of a grinder. The protective cover includes an arc-shaped outer peripheral portion that partially covers the outer periphery of a disk-shaped tool bit removably attached to the grinder. The cover attachment includes a first cover portion, a second cover portion, a first engagement member, and a second engagement member. The first cover portion is arc-shaped and configured to extend along the outer surface of the outer peripheral portion of the protective cover when the cover attachment is attached to the protective cover. The second cover portion is flat and extends from the first cover portion radially inward of the first cover portion. The first engagement member is provided near a first end of both circumferential ends of the first cover portion. The second engagement member is provided near a second end of both circumferential ends of the first cover portion.

[0007] The first engagement member is biased in a first direction relative to the first cover portion and configured to engage with a first end of the outer periphery of the protective cover when the cover attachment is attached to the protective cover. The first direction is a direction substantially parallel to a tangent to the first cover portion at the first end. The second engagement member is biased in a second direction relative to the first cover portion and configured to engage with a second end of the outer periphery of the protective cover when the cover attachment is attached to the protective cover. The second direction is a direction substantially parallel to a tangent to the first cover portion at the second end.

[0008] The cover attachment of this aspect is attached to the protective cover via a first engaging member and a second engaging member. The first engaging member is biased in a first direction and engages with a first end of the outer periphery of the protective cover, while the second engaging member is biased in a second direction and engages with a second end of the outer periphery of the protective cover. The first and second directions are substantially parallel to tangents of the first cover part at the first and second ends of the first cover part, respectively. Thus, the first and second engaging members are biased at both ends of the first cover part in directions optimal for pushing the outer periphery of the protective cover toward the first cover part of the cover attachment. This stabilizes the attachment state of the cover attachment to the protective cover. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a grinder with a wheel guard attached at the full push position. [Figure 2] FIG. 1 is a top view of a grinder with a wheel guard attached in the full push position. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. [Figure 5] FIG. 4 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 2 is a top view of the cover attachment. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 1 is a top view of a grinder with a wheel guard attached in a pull-off position. [Figure 9] FIG. [Figure 10] FIG. 10 is a cross-sectional view of a portion adjacent the first end of the cover attachment. [Figure 11] FIG. 4 is a perspective view of a first engagement member. [Figure 12]12 is another cross-sectional view of the portion adjacent to the first end of the cover attachment, corresponding to the cross-sectional view taken along line XII-XII in FIG. 3. [Figure 13] FIG. 10 is a cross-sectional view of an adjacent portion of the second end of the cover attachment. [Figure 14] FIG. 4 is a perspective view of a second engagement member. [Figure 15] FIG. 10 is a top view of the wheel guard and the cover attachment for explaining the installation of the cover attachment. [Figure 16] FIG. 10 is an explanatory diagram of the installation of the cover attachment. [Figure 17] FIG. 10 is an explanatory diagram of the installation of the cover attachment. [Figure 18] FIG. 10 is an explanatory diagram of the installation of the cover attachment. [Figure 19] FIG. 10 is a top view of a wheel guard and a cover attachment for illustrating the installation of the cover attachment according to another embodiment. [Figure 20] FIG. 10 is an explanatory diagram of the installation of the cover attachment. [Figure 21] FIG. 10 is an explanatory diagram of the installation of the cover attachment. DETAILED DESCRIPTION OF THE INVENTION

[0010] In one non-limiting embodiment of the present disclosure, the protective cover may include an outer periphery, a body-side cover, and a lip. The body-side cover may be flat, extend radially inward from one axial end of the outer periphery, and be configured to partially cover a first surface of the tool bit that faces the grinder body. The lip may protrude radially inward from the other axial end of the outer periphery. The first and second engagement members may each be configured to partially fit between the body-side cover and the lip in the axial direction of the outer periphery. According to this embodiment, the body-side cover and the lip restrict movement of the cover attachment in the axial direction of the outer periphery relative to the protective cover. This effectively reduces the possibility that the first engagement member and / or the second engagement member, and therefore the cover attachment, will come off the protective cover.

[0011] In addition to or instead of the above embodiment, the cover attachment may further include a first biasing member configured to bias the first engagement member in a first direction and a second biasing member configured to bias the second engagement member in a second direction. Each of the first biasing member and the second biasing member may be a coil spring. According to this embodiment, the first engagement member and the second engagement member can be reliably biased in the first and second directions with a simple configuration.

[0012] In addition to or instead of the above embodiment, the first cover portion may be configured to correspond to an arc of a substantially semicircle. The first direction and the second direction may be substantially parallel. According to this embodiment, a cover attachment with a simple shape and easy installation is realized.

[0013] In addition to or instead of the above embodiment, at least the first engagement member of the first and second engagement members may be configured to be moved, in response to manual operation by a user, from an engagement position where it can engage with a first end of the outer periphery of the protective cover to a retracted position where it cannot engage with the first end of the outer periphery. Note that "manual operation" here refers to direct operation by the user's hand. According to this embodiment, the user can manually operate at least the first engagement member as needed to attach or detach the cover attachment without using any additional tools.

[0014] In addition to or instead of the above embodiment, the first engagement member may be supported so as to be rotatable between the engagement position and the retracted position. Furthermore, the first engagement member may be supported by the first cover portion so as to be linearly movable in the first direction and rotatable about an axis substantially perpendicular to the first direction. According to this embodiment, a first engagement member with a rational configuration that is movable between the engagement position and the retracted position can be realized.

[0015] In addition to or instead of the above embodiment, the second engagement member may be supported by the first cover part so as to be movable substantially only in the second direction relative to the first cover part. According to this embodiment, the support structure for the second engagement member can be simplified.

[0016] In addition to or instead of the above embodiment, the first engagement member may be configured to move from a retracted position where it cannot engage with the first end of the outer periphery of the protective cover to an engagement position where it can engage with the first end of the outer periphery in response to the cover attachment being attached to the protective cover. According to this embodiment, the first engagement member automatically moves to the engagement position in response to the attachment of the cover attachment, thereby improving convenience compared to when manual operation of the first engagement member is required.

[0017] In addition to or instead of the above embodiment, the protective cover may include an outer peripheral portion and a body-side cover portion. The body-side cover portion may be flat, extend radially inward from one axial end of the outer peripheral portion, and be configured to partially cover a first surface of the tool bit that faces the body of the grinder. The second cover portion may be configured to partially cover a second surface of the tool bit that is opposite the first surface when the cover attachment is attached to the protective cover. The cover attachment may further include a protrusion that protrudes radially inward from an end of the first cover portion opposite the second cover portion in the axial direction. According to this embodiment, the protrusion abuts against the body-side cover portion of the protective cover, thereby restricting movement of the cover attachment toward the opposite side of the body of the grinder.

[0018] In addition to or instead of the above embodiment, the protective cover may be selectively fixable to a first or second position relative to the grinder body in the circumferential direction around the rotation axis of the tool bit during cutting operations using the grinder. The protrusion may be located so as not to overlap with the grinder body whether the cover attachment is attached to the protective cover in the first position or the second position. A specific attachment position (fixing position) may also be specified for the protective cover in response to the grinder body being used in a specific orientation relative to the workpiece during cutting operations. According to this embodiment, at least when the cover attachment is attached to the protective cover in the specific attachment position, it does not interfere with the grinder body. Therefore, even if the distance (gap) between the grinder body and the body-side cover portion of the protective cover is very small, cutting operations can be performed by selectively attaching the cover attachment to the protective cover.

[0019] In addition to or instead of the above embodiment, the protrusion may be thin-plate shaped. According to this embodiment, even if the distance (gap) between the grinder body and the body-side cover portion of the protective cover is relatively small, the protrusion can be placed in this gap, making it possible to use the cover attachment regardless of the placement of the protective cover. Furthermore, if the protrusion is thin-plate shaped, it is preferable that the protrusion be made of metal to ensure strength.

[0020] In addition to or instead of the above embodiment, the protrusion may be fixed to the first cover portion. This embodiment allows the protrusion to be easily provided on the cover attachment. If the protrusion is a thin metal plate, the protrusion may be molded integrally with the first and second resin cover portions. In this case, a compact, strong protrusion can be efficiently manufactured together with the first and second resin cover portions.

[0021] Representative and non-limiting embodiments of the present disclosure will be specifically described below with reference to the drawings.

[0022] First Embodiment A cover attachment 3A according to a first embodiment of the present disclosure will be described below with reference to Figures 1 to 18. The cover attachment 3A is an example of a cover attachment that can be selectively attached to a wheel guard 2 used in a handheld electric disc grinder 1 (hereinafter simply referred to as grinder 1).

[0023] First, a brief description will be given of the grinder 1. The grinder 1 is configured to perform various machining operations by rotating a disc-shaped tip tool 91. As shown in FIGS. 1 to 3, the grinder 1 includes a tool body 10, a motor 13, and a spindle 15.

[0024] The tool body 10 is a long, hollow body also referred to as a housing, and forms the outer shell of the grinder 1. The motor 13 and the spindle 15 are housed in the tool body 10. The motor 13 is arranged so that the rotation axis RX of the output shaft 131 extends in the longitudinal direction of the tool body 10. The spindle 15 is arranged in one end portion (hereinafter referred to as the head portion 101) of the tool body 10 in the longitudinal direction. The spindle 15 is supported in the head portion 101 so as to be rotatable about a drive axis DX. The drive axis DX extends in a direction intersecting (more specifically, substantially perpendicular to) the rotation axis RX of the output shaft 131.

[0025] One axial end of the spindle 15 is exposed to the outside from the tool body 10 and is configured as a tool mounting portion 150. The tool tip 91 is removably attached to the tool mounting portion 150 of the spindle 15. A part of the tool tip 91 is partially covered by a wheel guard 2 attached to the tool body 10.

[0026] In the following description, for convenience, the extending direction of the drive axis DX is defined as the up-down direction of the grinder 1. In the up-down direction, the side on which the tool mounting portion 150 of the spindle 15 is located defines the lower side of the grinder 1, and the opposite side defines the upper side of the grinder 1. The longitudinal direction of the tool body 10 (extending direction of the rotation axis RX of the motor 13) defines the front-to-rear direction of the grinder 1. In the front-to-rear direction, the side on which the head portion 101 is located defines the front side of the grinder 1, and the opposite side defines the rear side of the grinder 1. The direction perpendicular to the up-down direction and the front-to-rear direction defines the left-to-right direction of the grinder 1.

[0027] The rear of the tool body 10 is configured as a main handle 105. The main handle 105 is provided with a trigger switch 106 that can be pressed by the user. An auxiliary handle 18 is removably attached to the head 101 of the tool body 10. The head 101 is provided with a plurality of attachment portions 102 to which the auxiliary handles 18 can be attached so that the position and orientation of the auxiliary handle 18 can be selected depending on the type of processing work, restrictions on the work location, etc. In this embodiment, three attachment portions 102 are provided on the right side, left side, and top of the head 101.

[0028] When the trigger switch 106 is pressed by the user, the motor 13 is driven, and the power of the motor 13 drives the spindle 15 to rotate about the drive axis DX. Note that, although power is supplied to the grinder 1 of this embodiment from an external commercial power source via a power cord 19, the power source of the grinder 1 may also be a detachable rechargeable battery. In response to the rotation of the spindle 15, the tip tool 91 attached to the spindle 15 is rotated, and a processing operation is performed on the workpiece.

[0029] Grinding wheels, cutting wheels, blades, etc. are available as tool bits 91 that can be attached to the grinder 1. The user selects an appropriate tool bit 91 according to the desired processing work and attaches it to the grinder 1. Depending on the type of tool bit 91, the grinder 1 can perform processing work such as grinding, polishing, and cutting on the workpiece.

[0030] The wheel guard 2 will now be described. The wheel guard 2 is an example of a protective cover (also called a protective hood, wheel cover, disc cover, etc.) used to prevent sparks and dust generated during machining operations from scattering and to protect the user. The wheel guard 2 is attached to the tool body 10 and is configured to partially cover the tool bit 91.

[0031] 1 and 3, the wheel guard 2 of this embodiment is configured to be removably fixed to a cylindrical portion 103 that covers the periphery of the spindle 15 in the head portion 101 of the tool body 10. For convenience, in the following description, the up-down direction of the wheel guard 2 corresponds to the up-down direction of the grinder 1 when the wheel guard 2 is attached to the grinder 1. This also applies to the cover attachment 3A described below.

[0032] The wheel guard 2 of this embodiment is configured as a protective cover suitable for grinding and polishing work, and includes an attachment portion 21, an upper cover portion 23, an outer periphery portion 25, and a lip portion 27, as shown in Figures 2 to 4. In this embodiment, the upper cover portion 23, the outer periphery portion 25, the lip portion 27, and the attachment portion 21 are integrally formed from metal (e.g., steel plate). However, in another embodiment, the wheel guard 2 may be formed from a plurality of separate members that are connected and fixed to one another.

[0033] The mounting portion 21 is a portion that is fixed to the periphery of the cylindrical portion 103 of the tool body 10. The mounting portion 21 includes a cylindrical ring portion 211 that is divided at one location in the circumferential direction, and fastening portions 215 that bend from both ends of the divided portion (i.e., opening) of the ring portion 211 and extend radially outward. The fastening portions 215 have holes through which bolts 217 can be inserted. The ring portion 211 is disposed around the cylindrical portion 103 of the tool body 10 so that the central axis of the ring portion 211 substantially coincides with the drive shaft DX, and a nut is fastened to the bolt 217 that is inserted into the hole in the fastening portion 215. This firmly fixes the wheel guard 2 to the cylindrical portion 103.

[0034] The inner periphery of the ring portion 211 is provided with a plurality of protrusions 213 that protrude radially inward. The protrusions 213 are spaced apart from one another in the circumferential direction around the central axis of the ring portion 211. Although not shown in detail, the cylindrical portion 103 of the tool body 10 is provided with an annular groove that extends over the entire circumference around the drive shaft DX. With the protrusions 213 engaged with this annular groove, the position of the wheel guard 2 can be freely adjusted in the circumferential direction. This allows the user to secure the wheel guard 2 to the tool body 10 in an appropriate mounting position for the desired machining operation.

[0035] The upper cover part 23 is a flat plate-like part configured to partially cover an upper surface 911, which is one of two surfaces of the tool bit 91 attached to the tool attachment part 150 and faces the tool body 10. In this embodiment, the upper cover part 23 extends radially outward from the lower end of approximately half of the cylindrical attachment part 21. The upper cover part 23 is configured to cover an angular range of approximately 180 degrees around the central axis (drive shaft DX) of the upper surface 911 of the tool bit 91. In other words, the upper cover part 23 is in the shape of a substantially semicircular flat plate.

[0036] The outer peripheral portion 25 is configured to partially cover the outer periphery of the tool bit 91. The outer peripheral portion 25 is a plate-shaped portion curved in an arc, and extends circumferentially from one end to the other end of the outer edge of the substantially semicircular upper cover portion 23, and protrudes downward from the outer edge. The outer peripheral portion 25 is configured so that the lower end of the outer peripheral portion 25 is located lower than the lower end of the spindle 15 when the wheel guard 2 is attached to the tool body 10.

[0037] The lip portion 27 is a portion that protrudes radially inward from the lower edge of the outer circumferential portion 25 (i.e., the edge opposite the side on which the upper cover portion 23 is provided in the up-down direction). The lip portion 27 extends circumferentially from one end to the other end of the lower edge of the outer circumferential portion 25. The lip portion 27 is configured so that the inner edge of the lip portion 27 is located radially outward of the outer edge of the tool bit 91 when the wheel guard 2 is attached to the tool body 10 (cylindrical portion 103).

[0038] The cover attachment 3A will be described below.

[0039] The cover attachment 3A of this embodiment is configured to be selectively attached to a wheel guard 2 suitable for grinding and polishing work. The combination of the wheel guard 2 and the cover attachment 3A functions as a wheel guard 30A suitable for cutting work.

[0040] As shown in FIGS. 1 to 3 and 5, the cover attachment 3A includes an outer peripheral portion 31, a lower cover portion , a first engaging member 4A, a second engaging member 5, and an upper stopper .

[0041] The outer periphery portion 31 is a plate-shaped portion curved in an arc and configured to extend along the outer surface of the outer periphery portion 25 of the wheel guard 2 when the cover attachment 3A is attached to the wheel guard 2. More specifically, the outer periphery portion 31 is configured to correspond to the arc of a circle C2 that has a slightly larger diameter than a circle C1 that includes the arc that corresponds to the outer periphery portion 25 of the wheel guard 2. The circumferential length of the outer periphery portion 31 is set so that, when the cover attachment 3A is attached to the wheel guard 2, both ends of the outer periphery portion 25 protrude slightly from both ends of the outer periphery portion 31 in the circumferential direction.

[0042] The lower cover portion 36 is a flat portion configured to partially cover the underside 913 (see FIG. 3) of the tool bit 91 when the cover attachment 3A is attached to the wheel guard 2. In this embodiment, the lower cover portion 36 extends radially inward from the lower end of the outer circumferential portion 31. The shape of the lower cover portion 36 corresponds to a substantially semicircular shape (approximately half of the circle C2) that is slightly larger than the upper cover portion 23 of the wheel guard 2. In other words, the lower cover portion 36 is configured to cover an angular range of approximately 180 degrees around the central axis (drive shaft DX) of the underside 913 of the tool bit 91. Therefore, when the cover attachment 3A is attached to the wheel guard 2 and the wheel guard 30A is configured, approximately half of the semicircular shape of the tool bit 91 is covered from above, below, and radially outward by the wheel guard 30A.

[0043] The first engagement member 4A and the second engagement member 5 are respectively disposed near both circumferential ends (first end 311, second end 312) of the outer circumferential portion 31. The first engagement member 4A and the second engagement member 5 are configured to stably hold the cover attachment 3A to the wheel guard 2 by respectively engaging with both ends (first end 251, second end 252) of the outer circumferential portion 25 of the wheel guard 2 in a biased state. The first engagement member 4A and the second engagement member 5 will be described in detail later.

[0044] 3, 6, and 7, the upper stopper 38 is a protrusion that protrudes radially inward from the upper end of the outer circumferential portion 31. The upper stopper 38 is disposed above the upper cover portion 23 when the cover attachment 3A is attached to the wheel guard 2, and is configured to restrict downward movement of the cover attachment 3A relative to the wheel guard 2.

[0045] In this embodiment, when the wheel guard 2 is attached to the cylindrical portion 103, the gap in the vertical direction between the upper cover portion 23 and the tool body 10 is very small in the area located directly below the tool body 10 (particularly, the housing portion for the motor 13 behind the head portion 101). Therefore, the upper stopper 38 is formed in the shape of a thin plate that can be placed in this gap.

[0046] An elastic member 39 is fixed to the underside of the upper stopper 38. In this embodiment, the elastic member 39 is configured as an elastomer sheet. The elastic member 39 is configured to fill the gap between the upper cover portion 23 of the wheel guard 2 and the upper stopper 38.

[0047] In this embodiment, the outer circumferential portion 31 and the lower cover portion 36 are made of synthetic resin to reduce weight, whereas the upper stopper 38 is made of metal to ensure the necessary strength while being as thin as possible. More specifically, an L-shaped metal thin plate is integrated with the outer circumferential portion 31 by insert molding, and the upper stopper 38 is a part of this metal thin plate. The elastomer elastic member 39 may be formed as a separate member and then fixed to the upper stopper 38 by adhesive or the like, or may be molded integrally with the upper stopper 38, the outer circumferential portion 31, and the lower cover portion 36.

[0048] Furthermore, in this embodiment, the location of the upper stopper 38 is determined taking into consideration the typical mounting position of the wheel guard 30A during cutting operations. Specifically, cutting operations include so-called push cutting operations and pull cutting operations, and the posture of the grinder 1 and the mounting position of the wheel guard 2 (30A) suitable for each operation are different. This is because the grinder 1 rotates the tool bit 91 in only one direction around the drive shaft DX (specifically, clockwise when viewed from above), so the user needs to move the grinder 1 relative to the workpiece in accordance with the rotation direction of the part of the tool bit 91 that contacts the workpiece.

[0049] During push-cutting, the grinder 1 is pushed forward in an orientation such that the angle between the major axis of the tool body 10 (the rotation axis RX of the motor 13) and the surface of the workpiece is approximately 15 degrees, and the workpiece is cut by the portion of the tool bit 91 that is to the left of the drive axis DX. Therefore, as shown in FIG. 2, the auxiliary handle 18 is attached to the attachment portion 102 on the right side of the head portion 101. The wheel guard 2 is attached so that the portion of the tool bit 91 used for push-cutting is exposed to the outside and so that the hands gripping the main handle 105 and auxiliary handle 18 are protected. The attachment position of the wheel guard 2 at this time is also referred to as the push-cutting position.

[0050] On the other hand, during pull-cutting work, the grinder 1 is pulled rearward in an orientation such that the angle between the major axis of the tool body 10 (the rotation axis RX of the motor 13) and the surface of the workpiece is approximately 15 degrees, and the workpiece is cut by the portion of the tool bit 91 that is to the right of the drive axis DX. Therefore, as shown in FIG. 8, the auxiliary handle 18 is attached to the attachment portion 102 on the left side of the head portion 101. The wheel guard 2 is attached so that the portion of the tool bit 91 used for pull-cutting work is exposed to the outside and so that the hands gripping the main handle 105 and auxiliary handle 18 are protected. The attachment position of the wheel guard 2 at this time is also referred to as the pull-cutting position.

[0051] In this way, the appropriate angle (orientation) of the wheel guard 2 (30A) relative to the longitudinal axis of the tool body 10 (the rotation axis RX of the motor 13) differs between during pull-cutting operation and during push-cutting operation. In this embodiment, the upper stopper 38 is positioned so as not to overlap directly below the tool body 10, whether the cover attachment 3A is attached to the wheel guard 2 in the push-cut position or the pull-cut position. More specifically, the upper stopper 38 is positioned in the circumferential center of the outer circumferential portion 31.

[0052] In order to reliably move the upper stopper 38 out of the area directly below the tool body 10 in either of the above cases, it is preferable that the upper stopper 38 be within a predetermined range AR shown in FIG. 6. The range AR is a range within 35 degrees on either side of a straight line L that connects the center P of a circle C2 including an arc corresponding to the outer circumferential portion 31 to the circumferential center position of the outer circumferential portion 31. However, as described above, in this embodiment, the upper stopper 38 can be positioned in the vertical gap between the upper cover portion 23 and the tool body 10. Therefore, in such an example, the upper stopper 38 does not necessarily have to be positioned within the range AR.

[0053] The first engaging member 4A and the second engaging member 5 of the cover attachment 3A will be described in detail below.

[0054] 9 to 11, the first engaging member 4A is a separate member from the outer circumferential portion 31, and is supported by the outer circumferential portion 31 in the vicinity of the first end 311 so as to be movable relative to the outer circumferential portion 31. Therefore, a first support portion 32 that supports the first engaging member 4A is provided on the outer surface side of a portion of the outer circumferential portion 31 that is adjacent to the first end 311.

[0055] The first support portion 32 includes a pair of (two) support walls 321 and a spring receiving portion 323. The support walls 321 extend from the first end 311 of the outer circumferential portion 31 along the upper and lower ends of the outer circumferential portion 31, respectively. Both ends of a first shaft 325 are supported by the support walls 321. The first shaft 325 extends substantially in the up-down direction between the support walls 321. The spring receiving portion 323 is disposed between the support walls 321 on the opposite side of the first end 311 with respect to the first shaft 325.

[0056] The first engagement member 4A includes a long, plate-like main body 40 having a width slightly smaller than the spacing between the support walls 321, and a pair of protruding pieces 47 that bend and extend from both ends of the main body 40 in the width direction. In this embodiment, the main body 40 and the protruding pieces 47 are integrally formed of metal. The first engagement member 4A is disposed between the support walls 321 such that one surface of the main body 40 faces outward (toward the radially outer side of the outer circumferential portion 31) and the protruding pieces 47 extend radially inward of the outer circumferential portion 31 between the support walls 321. A long hole 471 is formed in each of the protruding pieces 47. The first shaft 325 is inserted through the long hole 471 and is slidable within the long hole 471.

[0057] With this configuration, the first engagement member 4A is supported by the first support portion 32 via the first shaft 325, and can move linearly relative to the outer circumferential portion 31 while being guided by the first shaft 325 and the elongated hole 471. In addition, the first engagement member 4A can rotate relative to the outer circumferential portion 31 around the axis of the first shaft 325.

[0058] Of the two longitudinal ends of the main body 40, the first end 41 closer to the first end 311 is bent in a U-shape (hook shape). More specifically, the first end 41 includes an extending portion 411 that extends linearly radially inward of the outer circumferential portion 31, and a tip portion 413 that bends from the tip of the extending portion 411. As will be described in detail later, the first end 41 is configured as a claw portion that engages with the first end 251 of the outer circumferential portion 25 of the wheel guard 2 (see FIG. 5). Therefore, the width of the first end 41 (more specifically, at least the tip portion 413) is set slightly smaller than the vertical distance between the upper cover portion 23 and the lip portion 27 of the wheel guard 2 (see FIG. 4).

[0059] Meanwhile, the other longitudinal end of the main body 40 (i.e., the second end 42 farther from the first end 311) is bent in an L-shape. The second end 42 protrudes between the support walls 321. A biasing spring 45 is disposed in a loaded state between the second end 42 and the spring receiving portion 323 of the first support portion 32. In other words, the second end 42 functions as a spring receiving portion. Furthermore, as will be described in detail later, the second end 42 also functions as an operating portion that is pressed by the user when the first engaging member 4A is moved linearly.

[0060] 5, the biasing spring 45 of this embodiment is a compression coil spring, and is disposed so that the central axis of the coil (i.e., the biasing direction of the biasing spring 45) is substantially parallel to a tangent line T1 of the circle C2 at the first end 311. Therefore, the first engaging member 4A is biased substantially parallel to the tangent line T1 in a direction in which the second end 42 moves away from the first end 311 of the outer circumferential portion 31 (in a direction in which the extension portion 411 of the first end 41 moves closer to the first end 311).

[0061] With this configuration, as shown in FIG. 10 , in an initial state where the cover attachment 3A is not attached to the wheel guard 2 and no force resisting the biasing force is applied to the first engagement member 4A, the first engagement member 4A is held in a position where the extension portion 411 abuts against the first end 311 of the outer circumferential portion 31. Hereinafter, the position of the first engagement member 4A with respect to the outer circumferential portion 31 at this time will also be referred to as the initial position. When the first engagement member 4A is in the initial position, a part of the first end 41 including the tip portion 413 is located inside the outer circumferential portion 31 relative to the first end 311, that is, within a substantially semicircular region (hereinafter simply referred to as the inner region) radially inside the outer circumferential portion 31. Furthermore, when the first engagement member 4A is in the initial position, the elongated hole 471 extends substantially parallel to the tangent line T1.

[0062] In this embodiment, the first support portion 32 is further provided with a stopper 327 shown in FIG. 10 and guide portions 328 and 329 shown in FIG.

[0063] The stopper 327 is configured to restrict rotation of the first engagement member 4A in the initial state, thereby stably holding the first engagement member 4A in the initial position. As shown in Fig. 10, the stopper 327 is a protrusion that protrudes radially outward from the first end 311. One surface of the stopper 327 forms a flat surface that is continuous with the first end 311, and by abutting against the extension portion 411 of the first end portion 41, it is possible to effectively restrict rotation of the first engagement member 4A that is in the initial position in a biased state.

[0064] 12 are configured to restrict the rotation of the first engagement member 4A and, together with the first shaft 325, to guide the first engagement member 4A substantially parallel to the tangent line T1 relative to the outer circumferential portion 31. More specifically, the guide portions 328, 329 are configured to abut against abutment portions 478, 479 of the pair of protruding pieces 47 (see FIG. 11) of the first engagement member 4A on both sides of the first shaft 325 in the longitudinal direction of the first engagement member 4A.

[0065] The guide portions 328 protrude radially outward from the outer circumferential portion 31 on the opposite side of the first end 311 with respect to the first shaft 325. More specifically, the guide portions 328 are disposed adjacent to the inner surface of the support wall portion 321 on both sides of the spring receiving portion 323 (see FIG. 10), and are configured as a pair of protrusions that can abut against the abutment portions 478 of the pair of protrusion pieces 47 (only one of the protrusions is shown in FIG. 12). The abutment portions 478 are end portions of the protrusion pieces 47 that are on the second end portion 42 side in the longitudinal direction of the first engagement member 4A.

[0066] The guide portions 329 protrude radially outward from the outer circumferential portion 31 on the same side as the first end 311 with respect to the first shaft 325. More specifically, the guide portions 329 are disposed adjacent to the inner surface of the support wall portion 321 on both sides of the stopper 327 (see FIG. 10), and are configured as a pair of protrusions that can abut against abutment portions 479 of the pair of protrusion pieces 47 (only one of the protrusions is shown in FIG. 12). The abutment portions 479 are end portions of the protrusion pieces 47 that are on the first end portion 41 side in the longitudinal direction of the first engagement member 4A.

[0067] The protruding ends of the guide portions 328 and 329 each include a plane that is substantially parallel to the tangent line T1. Therefore, when the protruding ends of the abutment portions 478 and 479 are in contact with the planes of the protruding ends of the guide portions 328 and 329, the first engagement member 4A is restricted from rotating about the axis of the first shaft 325 and is guided to move substantially parallel to the tangent line T1.

[0068] When a force resisting the biasing force of the biasing spring 45 is applied to the first engagement member 4A, the first end 41 is movable from its initial position substantially parallel to the tangent line T1 in a direction away from the first end 311, and the first engagement member 4A is rotatable around the axis of the first shaft 325. As will be described in detail later, when the cover attachment 3A is attached to the wheel guard 2, the first engagement member 4A is moved from its initial position in response to manual operation by the user. Therefore, to enable manual operation by the user, most of the main body 40 of the first engagement member 4A is exposed to the outside from the support wall 321.

[0069] 9, 13, and 14, the second engagement member 5, like the first engagement member 4A, is a separate member from the outer circumferential portion 31, and is supported by the outer circumferential portion 31 in the vicinity of the second end 312 so as to be movable relative to the outer circumferential portion 31. For this reason, a second support portion 33 that supports the second engagement member 5 is provided on the outer surface side of the portion of the outer circumferential portion 31 that is adjacent to the second end 312.

[0070] The second support portion 33 includes a pair of (two) support walls 331 and a spring bearing portion 333. The support walls 331 extend from the second end 312 of the outer peripheral portion 31 along the upper and lower ends of the outer peripheral portion 31, respectively. The support walls 331 support both ends of two second shafts 335. The second shafts 335 are spaced apart from each other in the extension direction of a tangent T2 to the circle C2 at the second end 312. The second shafts 335 extend parallel to each other between the support walls 331 in a substantially vertical direction. The spring bearing portion 333 is disposed between the support walls 331 on the opposite side of the second end 312 from the two second shafts 335.

[0071] Similar to the first engagement member 4A, the second engagement member 5 includes a long, plate-like main body 50 having a width slightly smaller than the spacing between the support walls 321, and a pair of protruding pieces 57 that bend and extend from both ends of the main body 50 in the width direction. In this embodiment, the main body 50 and the protruding pieces 57 are integrally formed from metal. The second engagement member 5 is disposed between the support walls 331. A long hole 571 is formed in each of the protruding pieces 57. The second shaft 335 is inserted through the long holes 571 and is slidable within the long holes 571.

[0072] The first engagement member 4A is supported by the first support portion 32 via only one first shaft 325, whereas the second engagement member 5 is supported by the second support portion 33 via two second shafts 335. Therefore, the second engagement member 5 can only move linearly while being guided by the second shafts 335 and the elongated holes 571.

[0073] Of the two longitudinal ends of the main body 50, the first end 51, which is closer to the second end 312, is bent in a U-shape (hook shape). More specifically, the first end 51 includes an extending portion 511 that extends linearly radially inward from the outer circumferential portion 31, and a tip portion 513 that bends from the tip of the extending portion 511. As will be described in detail later, the first end 51 is configured as a claw portion that engages with the second end 252 of the outer circumferential portion 25 of the wheel guard 2 (see FIG. 5). Therefore, similar to the first end 41 of the first engagement member 4A, the width of the first end 51 (more specifically, at least the tip portion 513) is set slightly smaller than the vertical distance between the upper cover portion 23 and the lip portion 27 of the wheel guard 2 (see FIG. 4).

[0074] Meanwhile, the other longitudinal end of the main body 50 (i.e., the second end 52 farther from the second end 312) is bent in an L-shape. The second end 52 protrudes between the support walls 331. A biasing spring 55 is disposed in a loaded state between the second end 52 and the spring receiving portion 333 of the second support portion 33. In other words, the second end 52 functions as a spring receiving portion.

[0075] 5, the biasing spring 55 of this embodiment is a compression coil spring, and is disposed so that the central axis of the coil (i.e., the biasing direction of the biasing spring 55) is substantially parallel to the tangent line T2 of the circle C2 at the second end 312. Therefore, the second engaging member 5 is biased substantially parallel to the tangent line T2 in a direction in which the second end 52 moves away from the second end 312 of the outer circumferential portion 31 (in a direction in which the extension portion 511 of the first end 51 moves closer to the second end 312). Note that the biasing spring 55 of this embodiment is a compression coil spring with the same specifications as the biasing spring 45. This reduces parts costs and the possibility of errors during assembly.

[0076] 13 , in the initial state where the cover attachment 3A is not attached to the wheel guard 2 and no force acting against the biasing force is applied to the second engagement member 5, the second engagement member 5 is held in a position where the extension portion 511 of the first end portion 51 abuts the second end 312 of the outer circumferential portion 31. Hereinafter, the position of the second engagement member 5 with respect to the outer circumferential portion 31 at this time will also be referred to as the initial position. As with the first engagement member 4A, when the second engagement member 5 is in the initial position, a portion of the second end 52 including the tip portion 513 is positioned more inward of the second end 312 of the outer circumferential portion 31, i.e., within the inner region. Furthermore, when the second engagement member 5 is in the initial position, the elongated hole 571 extends substantially parallel to the tangent line T2.

[0077] When a force is applied that resists the biasing force of the biasing spring 55, the second engagement member 5 can move from its initial position substantially parallel to the tangent line T2 in a direction in which the first end 51 moves away from the second end 312.

[0078] As described above, when the first engagement member 4A and the second engagement member 5 are both in their initial positions, a portion of each of the first end portions 41, 51 protrudes into the inner region of the outer periphery 31. Therefore, in order to attach the cover attachment 3A to the wheel guard 2, at least one of the first end portions 41, 51 needs to be retracted outside the inner region of the outer periphery 31. In this embodiment, to reduce the effort required for manual operation, only the first engagement member 4A is rotatable as described above, and only the first end portion 41 is movable outside the inner region.

[0079] On the other hand, the second engagement member 5, which does not need to be manually operated for rotation, is entirely disposed inside the support wall portion 331 except for the first end portion 51, and is covered by the support wall portion 331 and a cover portion 338 attached to the support wall portion 331. In other words, only the first end portion 51 of the second engagement member 5 is exposed to the outside of the second support portion 33.

[0080] The attachment of the cover attachment 3A to the wheel guard 2 and the removal of the cover attachment 3A from the wheel guard 2 will be described below.

[0081] When attaching the cover attachment 3A, the user first hooks the tip 513 of the first end 51 (claw portion) of the second engagement member 5 onto the second end 252 of the wheel guard 2, as shown in FIGS. 15 and 16 . At this time, the first engagement member 4A side of the cover attachment 3A is separated from the first end 251 of the wheel guard 2. Then, the user rotates the wheel guard 2 relative to the cover attachment 3A, using the second end 252 of the wheel guard 2 as a fulcrum, in a direction in which the wheel guard 2 fits into the internal region of the outer circumferential portion 31 (see arrow A1 in FIG. 15 ). During this process, the first end 51 of the second engagement member 5 abuts against and is pressed against the second end 252 of the outer circumferential portion 25, and the second engagement member 5 is moved linearly from its initial position substantially parallel to the tangent line T2 in a direction in which the first end 51 moves away from the second end 312 (see arrow A2 in FIG. 16 ).

[0082] The user also manually operates the first engagement member 4A to retract the first end 41 of the first engagement member 4A from the inner region. More specifically, as shown in Figure 17, the user first presses the second end 42 so as to push it between the support wall portions 321, thereby moving the first engagement member 4A in a linear manner (see arrow A3). For ease of explanation, Figure 17 shows the wheel guard 2 attached to the cover attachment 3A. This is also true for Figure 18, which will be referred to later.

[0083] The first engaging member 4A is moved linearly from the initial position generally parallel to the tangent line T1 in a direction in which the first end 41 moves away from the first end 311, against the biasing force of the biasing spring 45. At this time, the first engaging member 4A is guided by the first shaft 325 inserted through the elongated hole 471 and the guide portions 328 and 329 (see FIG. 12) that abut against the abutment portions 478 and 479, respectively, as described above, and is moved substantially parallel to the tangent line T1.

[0084] When the first end 41 of the first engagement member 4A is moved to a certain extent in a direction away from the first end 311, the tip end 413 of the first engagement member 4A can rotate without interfering with the outer peripheral portion 31. The first engagement member 4A can also rotate without interference between the abutment portion 478 and the guide portion 328 (see FIG. 12). The position of the first engagement member 4A at this time (the position shown in FIG. 17) is also referred to as the intermediate position. As shown in FIG. 18, the user presses the second end 42 and rotates the first engagement member 4A in a direction (diametrically outward) in which the tip end 413 moves away from the inner region (see arrow A4), thereby retracting the first end 41 from the inner region. The position of the first engagement member 4A in which the first end 41 is retracted from the inner region of the outer peripheral portion 31 (the position shown in FIG. 18) is also referred to as the retracted position. The first engagement member 4A in the retracted position allows the wheel guard 2 to enter and leave the inner region without interfering with the wheel guard 2.

[0085] Furthermore, the user adjusts the wheel guard 2 to the appropriate mounting position so that the outer periphery 25 of the wheel guard 2 fits into the inner region along the inner surface of the outer periphery 31 of the cover attachment 3A. When the wheel guard 2 is placed in the appropriate mounting position, both ends of the outer periphery 25 of the wheel guard 2 protrude from both circumferential ends of the outer periphery 31 of the cover attachment 3A.

[0086] Thereafter, the user rotates the first engagement member 4A in a direction (radially inward) such that the tip end portion 413 enters the inner region (see arrow A5 in FIG. 18 ) and positions the tip end portion 413 inside the first end 251 of the outer circumferential portion 25 of the wheel guard 2. In other words, the first engagement member 4A is returned to the intermediate position. In this state, when the user stops pressing the second end 42 of the first engagement member 4A, the biasing force of the biasing spring 45 causes the first engagement member 4A to move linearly, substantially parallel to the tangent line T1, in a direction in which the first end 41 approaches the first end 311 (see arrow A6 in FIG. 17 ).

[0087] As described above, the outer peripheral portion 31 of the cover attachment 3A is configured so that both ends of the outer peripheral portion 25 of the wheel guard 2 protrude from both circumferential ends of the outer peripheral portion 31. Therefore, as shown in FIG. 5 , the first engagement member 4A is held in a position where the extending portion 411 of the first end portion 41 abuts against the first end 251 of the outer peripheral portion 25 and the tip portion 413 faces the inner surface of the outer peripheral portion 25. The position of the first engagement member 4A at this time is also referred to as the engagement position of the first engagement member 4A. Furthermore, the second engagement member 5 is held in a position where the extending portion 511 of the first end portion 51 abuts against the second end 252 of the outer peripheral portion 25 and the tip portion 513 faces the inner surface of the outer peripheral portion 25. The position of the second engagement member 5 at this time is also referred to as the engagement position of the second engagement member 5.

[0088] When the first engagement member 4A and the second engagement member 5 are placed in their respective engagement positions, the installation of the cover attachment 3A is complete. The first end 41 (extension 411) of the first engagement member 4A is urged by the urging spring 45 in a direction substantially parallel to the tangent line T1 and pressed against the first end 251. Similarly, the first end 51 (extension 511) of the second engagement member 5 is urged by the urging spring 55 in a direction substantially parallel to the tangent line T2 and pressed against the second end 252.

[0089] When removing the cover attachment 3A, the user first presses the second end 42 of the first engagement member 4A, as in the case of attachment, and moves the first engagement member 4A linearly from the engagement position (see FIG. 5) to the intermediate position (see FIG. 17). Once the first engagement member 4A is positioned in the intermediate position, the user rotates the first engagement member 4A radially outward to the retracted position (see FIG. 18) while pressing the second end 42, thereby retracting the first end 41 from the inner region of the outer periphery 31. The user then rotates the wheel guard 2, using the second end 252 of the wheel guard 2 as a fulcrum, in a direction in which the outer periphery 25 moves away from the outer periphery 31.

[0090] Thereafter, the user releases the engagement between the second end 252 of the outer circumferential portion 25 and the tip end 513 of the second engagement member 5, and separates the cover attachment 3A from the wheel guard 2. The first end 51 of the second engagement member 5 is urged by the urging spring 55 in a direction substantially parallel to the tangent line T2, and returns to the initial position (see FIG. 13). When the user rotates the first engagement member 4A to the intermediate position and stops pressing, the first engagement member 4A is urged by the urging spring 45 in a direction substantially parallel to the tangent line T1, and returns to the initial position (see FIG. 10).

[0091] As described above, in this embodiment, the cover attachment 3A is attached to the wheel guard 2 via the first and second engagement members 4A and 5, which are provided at both ends of the outer periphery 31 and engage with both ends of the outer periphery 25 in a biased state. The first engagement member 4A is biased substantially parallel to a tangent line T1 at the first end 311 of the outer periphery 31. The second engagement member 5 is biased substantially parallel to a tangent line T2 at the second end 312 of the outer periphery 31. In other words, the first and second engagement members 4A and 5 are biased at both ends of the outer periphery 31 in a direction that is optimal for pressing the outer periphery 25 of the wheel guard 2 toward the outer periphery 31 of the cover attachment 3A. This stabilizes the attachment state of the cover attachment 3A to the wheel guard 2.

[0092] In this embodiment, the biasing springs 45, 55 are attached so as to apply substantially the same magnitude of biasing force when the first engagement member 4A and the second engagement member 5 are in the engaged position, thereby maintaining the wheel guard 2 in a well-balanced manner.

[0093] Furthermore, the extending portions 411, 511 of the first engagement member 4A and the second engagement member 5 abut against both ends of the outer periphery 25 of the wheel guard 2, and the tip portions 413, 513 fit inside the outer periphery 25 to engage with the wheel guard 2. The tip portions 413, 513 fit between the upper cover portion 23 and the lip portion 27 in the vertical direction, so that the upper cover portion 23 and the lip portion 27 restrict vertical movement of the cover attachment 3A. This effectively reduces the possibility that the first engagement member 4A and / or the second engagement member 5, and therefore the cover attachment 3A, will come off the wheel guard 2.

[0094] Compared to both ends firmly attached to the outer periphery 25 by the first engaging member 4A and the second engaging member 5, the portions of the outer periphery 31 that are relatively far from both ends of the outer periphery 25 (particularly the circumferential center portion) are more likely to move up and down relative to the wheel guard 2. In contrast, in this embodiment, the upper stopper 38 located in the circumferential center portion of the outer periphery 31 can effectively restrict downward movement of the cover attachment 3A relative to the wheel guard 2.

[0095] Furthermore, in order to prevent relative movement (loosening and rattle) between the wheel guard 2 and the cover attachment 3A in the vertical direction, it is preferable that the tip portions 413, 513 fit between the upper cover portion 23 and the lip portion 27 with substantially no gap. However, due to manufacturing constraints and errors, unintended gaps may occur in the vertical direction between the tip portions 413, 513 and the upper cover portion 23 and / or the lip portion 27. In response to this, the elastic member 39 arranged on the underside of the upper stopper 38 abuts against the upper cover portion 23 and presses it against the tip portions 413, 513, thereby effectively reducing the relative movement in the vertical direction between the wheel guard 2 and the cover attachment 3A.

[0096] Second Embodiment A cover attachment 3B according to a second embodiment of the present disclosure will be described below with reference to Figures 19 to 21. Note that the configuration of the cover attachment 3B of the second embodiment, except for a portion of the first engaging member 4B, is substantially the same as that of the cover attachment 3A of the first embodiment (including cases where the shape is slightly different). Therefore, in the following, the configuration of the cover attachment 3B that is substantially the same as that of the cover attachment 3A of the first embodiment will be assigned the same reference numerals and description thereof will be omitted or simplified, and different configurations will be mainly described.

[0097] The first engagement member 4B of the cover attachment 3B of the second embodiment is configured to automatically engage with the wheel guard 2 when the cover attachment 3B is attached to the wheel guard 2, without manual operation by the user.

[0098] More specifically, as shown in FIG. 19 , the first engagement member 4B is supported by the outer circumferential portion 31 via the first support portion 32, as in the first embodiment. In this embodiment, the second end 42 of the first engagement member 4B is longer than in the first embodiment. Furthermore, the outer circumferential portion 31 is formed with an opening 322 that connects the inner region of the outer circumferential portion 31 with the outside (the region on the support wall portion 321 side). The first engagement member 4B is rotationally biased so that the tip of the second end 42 protrudes into the inner region through the opening 322. Therefore, when the cover attachment 3B is not attached to the wheel guard 2, the first engagement member 4B is disposed in the retracted position, and the first end 41 is outside the inner region of the outer circumferential portion 31.

[0099] As shown in Figure 19, when attaching the cover attachment 3B, as in the first embodiment, the user hooks the tip 513 of the first end 51 (claw portion) of the second engagement member 5 onto the second end 252 of the wheel guard 2 (see Figure 16).Then, the user rotates the wheel guard 2 relative to the cover attachment 3B, using the second end 252 as a fulcrum, and pushes it in so that the outer periphery 25 approaches the outer periphery 31.

[0100] 20, the outer surface of the outer periphery 25 of the wheel guard 2 abuts against the tip of the second end 42 protruding into the inner region through the opening 322. When the user pushes the wheel guard 2 further, the outer periphery 25 presses against the first engagement member 4B, causing the second end 42 to rotate so as to retract from the inner region through the opening 322 (see arrow A7).

[0101] As shown in Figure 21, when the wheel guard 2 reaches the installation position, the first engagement member 4B is moved to the engagement position by the biasing force of the biasing spring 45 (see Figure 11) and is held in the engagement position, thereby completing the installation of the cover attachment 3B and forming a wheel guard 30B suitable for cutting work.

[0102] As described above, in this embodiment, the first engagement member 4B is configured to automatically move from the retracted position to the engagement position in response to the cover attachment 3B being attached to the wheel guard 2. In other words, a highly convenient cover attachment 3B is realized, which does not require the user to manually move the first engagement member 4B from the retracted position to the engagement position.

[0103] The correspondence between each component (feature) of the above embodiment and each component (feature) of the present disclosure or invention is shown below. However, each component of the embodiment is merely an example and does not limit each component of the present disclosure or invention.

[0104] The grinder 1 is an example of a "grinder." The tool bit 91, the upper surface 911, and the lower surface 913 are examples of a "disc-shaped tool bit," a "first surface," and a "second surface," respectively. The wheel guard 2, the outer periphery 25, the upper cover portion 23, and the lip portion 27 are examples of a "protective cover," a "outer periphery," a "main body cover portion," and a "lip portion," respectively. Each of the cover attachments 3A and 3B is an example of a "cover attachment." The outer periphery 31, the lower cover portion 36, and the upper stopper 38 are examples of a "first cover portion," a "second cover portion," and a "protrusion," respectively. Each of the first engaging members 4A and 4B is an example of a "first engaging member." The second engaging member 5 is an example of a "second engaging member." The first end 311 and the second end 312 of the outer periphery 31 of the cover attachments 3A and 3B are examples of a "first end of the first cover portion" and a "second end of the first cover portion," respectively. The first end 251 and the second end 252 of the outer circumferential portion 25 of the wheel guard 2 are examples of the "first end of the protective cover" and the "second end of the protective cover", respectively. The biasing springs 45 and 55 are examples of the "first biasing member" and the "second biasing member", respectively.

[0105] It should be noted that the above-described embodiments are merely examples, and the cover attachments according to the present disclosure are not limited to the illustrated cover attachments 3A and 3B. For example, the following modifications may be made. Furthermore, at least one of these modifications may be adopted in combination with the cover attachments 3A and 3B illustrated in the embodiments and at least one of the features described in each claim.

[0106] For example, the protective cover to which the cover attachments 3A and 3B according to the present disclosure can be attached is not limited to the wheel guard 2. The cover attachments 3A and 3B may be applied to any protective cover as long as they have an outer periphery that matches the length and width of the outer periphery 31 and the first engagement members 4A and 4B can be engaged with both ends of the outer periphery.

[0107] In the above embodiment, the wheel guard 2 is configured to cover an angular range of approximately 180 degrees around the central axis of the tool bit 91. However, if the protective cover to be applied is configured to cover an angular range of the tool bit 91 greater than 180 degrees, the circumferential length of the outer circumferential portion 31 of the cover attachments 3A, 3B may be changed accordingly. In accordance with the change in the outer circumferential portion 31, the direction in which the first engagement members 4A, 4B and the second engagement member 5 are biased may be changed to match the extending direction of the tangents at both ends of the outer circumferential portion 31.

[0108] The shapes, materials, biasing manner, and movement manner of the first engagement members 4A, 4B and the second engagement member 5 can be appropriately changed from the examples of the above embodiment.

[0109] For example, the first end portions 41 of the first engagement members 4A, 4B may be bent in an L-shape instead of a U-shape (hook-like). In other words, the first end portion 41 may omit the tip portion 413 and include only the extension portion 411. A similar modification is possible for the first end portion 51 of the second engagement member 5. In this modification, in order to reduce the possibility of the cover attachments 3A, 3B coming off the wheel guard 2, it is preferable that the extension portion 411 be fitted between the upper cover portion 23 and the lip portion 27 of the wheel guard 2 in the vertical direction. Therefore, it is preferable that the wheel guard 2 be configured so that both end portions of the upper cover portion 23 and the lip portion 27 protrude beyond both circumferential ends of the outer circumferential portion 25.

[0110] The first engagement members 4A, 4B and the second engagement member 5 may be biased by a biasing member other than the biasing springs 45, 55. For example, at least one of the biasing springs 45, 55 may be changed to a type of spring other than a compression coil spring, or to rubber or synthetic resin.

[0111] Furthermore, the first engagement member 4A may be configured to move linearly between the engagement position and the retracted position in a direction substantially parallel to the tangent line T1 and in a direction intersecting the tangent line T1, for example, in response to manual operation by the user.

[0112] In the first embodiment, only the first engagement member 4A is configured to be moved between the engagement position and the retracted position in response to manual operation by the user. However, the second engagement member 5 may also be configured similarly to the first engagement member 4A and be movable between the engagement position and the retracted position in response to manual operation by the user. According to this embodiment, the user can selectively use either the first engagement member 4A or the second engagement member 5, whichever is easier to manually operate, depending on factors such as dominant hand, the positioning of the cover attachment 3A relative to the grinder 1, and restrictions on the work location.

[0113] The material, shape, position, and / or number of the upper stopper 38 are not limited to those illustrated in the above embodiment, as long as it is capable of restricting downward movement of the cover attachment 3A relative to the wheel guard 2. For example, one or more upper stoppers 38 made of synthetic resin may be provided within the above range AR, integrally molded with the outer periphery 31 and the lower cover portion 36. Alternatively, the upper stopper 38 may be formed as a separate member from the outer periphery 31 and then fixed to the outer periphery 31 by, for example, screwing, snap fitting, or adhesive.

[0114] The elastic member 39 for restricting the relative movement between the wheel guard 2 and the cover attachments 3A and 3B in the vertical direction may be made of an elastic material other than elastomer (e.g., rubber or synthetic resin foam). Alternatively, a spring (e.g., a leaf spring) may be used as the elastic member 39.

[0115] Furthermore, the elastic member 39 may be interposed between a portion of the cover attachment 3A, 3B other than the upper stopper 38 and a portion of the wheel guard 2. For example, the elastic member 39 may be provided on a surface of the extending portion 411 of the first engagement member 4A, 4B that abuts against the first end 251 of the outer circumferential portion 25 of the wheel guard 2, and on a surface of the extending portion 511 of the second engagement member 5 that abuts against the second end 252 of the outer circumferential portion 25. The elastic member 39 may be provided on the upper and lower surfaces of the tip end portion 413 of the first engagement member 4A, 4B and the upper and lower surfaces of the tip end portion 513 of the second engagement member 5. The elastic member 39 may be provided on at least a portion of the inner surface of the outer circumferential portion 31. The elastic member 39 may be provided on at least a portion of a circular-arc region of the lower cover portion 36 that faces the lip portion 27 of the wheel guard 2. The type and shape of the elastic member 39 may be selected appropriately depending on the arrangement.

[0116] In view of the spirit of the present invention and the above-described embodiments, the following aspects are constructed, and at least one of the following aspects may be adopted in combination with the features of the embodiments and their variants, or at least one of the features described in each claim. [Aspect 1] Of the first engagement member and the second engagement member, only the first engagement member is configured to be moved in response to a manual operation. [Aspect 2] At least one of the first engaging member and the second engaging member has a claw portion formed in a U-shape (hook shape), the claw portion is configured to engage with the outer periphery of the protective cover such that a tip portion of the claw portion faces an inner surface of the outer periphery of the protective cover, The tip of the claw is configured to fit between the body-side cover portion and the lip portion of the protective cover. Each of the first end portions 41 of the first engaging members 4A and 4B and the first end portion 51 of the second engaging member 5 is an example of a "claw portion" in this embodiment. Each of the tip portions 413 and 513 is an example of a "tip portion of a claw portion." [Aspect 3] The first cover portion has a restricting portion configured to restrict the first engaging member from rotating about the axis when the first engaging member moves linearly in the first direction. The guide portions 328 and 329 are an example of the "restriction portion" of this embodiment. [Aspect 4] The protrusion is only one and is disposed at the center in the circumferential direction of the first cover portion. [Aspect 5] The first biasing member and the second biasing member are configured to apply substantially the same magnitude of biasing force to the first engaging member and the second engaging member. [Explanation of symbols]

[0117] 1: Electric disc grinder (grinder), 10: Tool body, 101: Head, 102: Mounting part, 103: Cylinder, 105: Main handle, 106: Trigger switch, 13: Motor, 131: Output shaft, 15: Spindle, 150: Tool mounting part, 18: Auxiliary handle, 19: Power cord, 2: Wheel guard, 21: Mounting part, 211: Ring, 213: Protrusion 215: fastening portion, 217: bolt, 23: upper cover portion, 25: outer periphery, 251: first end, 252: second end, 27: lip portion, 3A, 3B: cover attachment, 30A, 30B: wheel guard, 31: outer periphery, 311: first end, 312: second end, 32: first support portion, 321: support wall portion, 322: opening, 323: spring receiving portion, 325: first shaft, 327: stopper, 328: guide portion, 329: guide portion, 33: second support portion, 331: support wall portion, 333: spring receiving portion, 335: second shaft, 338: cover portion, 36: lower cover portion, 38: upper stopper, 39: elastic member, 4A, 4B: first engaging member, 40: main body portion, 41: first end portion, 411: extension portion, 413: tip portion, 42: second end portion, 45: biasing spring, 47: projection Projection piece, 471: oblong hole, 478: abutment portion, 479: abutment portion, 5: second engagement member, 50: main body portion, 51: first end portion, 511: extension portion, 513: tip portion, 52: second end portion, 55: biasing spring, 57: projection piece, 571: oblong hole, 91: tip tool, 911: upper surface, 913: lower surface, DX: drive shaft, RX: rotation shaft, C1: circle, C2: circle, P: center of circle C2, T1: tangent, T2: tangent, AR: range

Claims

1. A cover attachment that can be attached to a protective cover including an arc-shaped outer periphery that partially covers the outer periphery of a disk-shaped tool bit that is removably attached to a grinder, an arc-shaped first cover portion configured to extend along an outer surface of the outer periphery of the protective cover when the cover attachment is attached to the protective cover; a flat plate-shaped second cover portion extending from the first cover portion radially inward of the first cover portion; a first engaging member provided near a first end of both circumferential ends of the first cover portion; a second engaging member provided in the vicinity of a second end of the first cover portion, the first engaging member is biased relative to the first cover portion in a first direction substantially parallel to a tangent line of the first cover portion at the first end, and is configured to engage with a first end of the outer periphery of the protective cover when the cover attachment is attached to the protective cover; A cover attachment characterized in that the second engagement member is biased relative to the first cover portion in a second direction substantially parallel to a tangent line of the first cover portion at the second end, and is configured to engage with the second end of the outer periphery of the protective cover when the cover attachment is attached to the protective cover.

2. 2. The cover attachment according to claim 1, The protective cover includes: (i) the outer circumferential portion; (ii) a flat-plate-shaped body-side cover portion extending from one axial end of the outer circumferential portion toward the radially inner side of the outer circumferential portion and configured to partially cover a first surface of the tool bit that faces the body of the grinder; and (iii) a lip portion protruding radially inward from the other axial end of the outer circumferential portion. A cover attachment characterized in that the first engaging member and the second engaging member are each configured to partially fit between the main body side cover portion and the lip portion in the axial direction of the outer periphery.

3. 3. The cover attachment according to claim 1 or 2, a first biasing member configured to bias the first engagement member in the first direction; a second biasing member configured to bias the second engagement member in the second direction.

4. 4. The cover attachment according to claim 3, A cover attachment, wherein each of the first biasing member and the second biasing member is a coil spring.

5. The cover attachment according to any one of claims 1 to 4, The first cover portion is configured to correspond to an arc of a substantially semicircle, A cover attachment, wherein the first direction and the second direction are substantially parallel to each other.

6. The cover attachment according to any one of claims 1 to 5, A cover attachment characterized in that, of the first engaging member and the second engaging member, at least the first engaging member is configured to be moved between an engaging position where it can engage with the first end of the outer periphery of the protective cover and a retracted position where it cannot engage with the first end of the outer periphery in response to manual operation by a user.

7. 7. The cover attachment according to claim 6, A cover attachment, wherein the first engagement member is supported so as to be rotatable between the engagement position and the retracted position.

8. 8. The cover attachment according to claim 7, A cover attachment characterized in that the first engagement member is supported on the first cover portion so as to be movable linearly in the first direction and rotatable around an axis substantially perpendicular to the first direction.

9. The cover attachment according to any one of claims 6 to 8, A cover attachment, wherein the second engagement member is supported by the first cover portion so as to be movable substantially only in the second direction relative to the first cover portion.

10. The cover attachment according to any one of claims 1 to 5, A cover attachment characterized in that the first engagement member is configured to move from a retracted position in which it cannot engage with the first end of the outer periphery of the protective cover to an engagement position in which it can engage with the first end of the outer periphery in response to the cover attachment being attached to the protective cover.

11. A cover attachment according to any one of claims 1 to 10, the protective cover includes: (i) the outer peripheral portion; and (ii) a flat-plate-shaped body-side cover portion extending from one axial end of the outer peripheral portion toward a radially inner side of the outer peripheral portion and configured to partially cover a first surface of the tool bit that faces the body of the grinder, the second cover portion is configured to partially cover a second surface of the tool bit opposite to the first surface when the cover attachment is attached to the protective cover, The cover attachment further includes a protrusion that protrudes radially inward from an end of the first cover portion opposite the second cover portion in the axial direction.

12. 12. The cover attachment of claim 11, the protective cover can be selectively fixed to a first position or a second position with respect to the body of the grinder in a circumferential direction around the rotation axis of the tool bit during cutting work using the grinder, A cover attachment characterized in that the protrusion is located in a position that does not overlap with the main body of the grinder, both when the cover attachment is attached to the protective cover in the first position and when the cover attachment is attached to the protective cover in the second position.

13. 13. The cover attachment according to claim 11 or 12, A cover attachment characterized in that the protrusion is in the shape of a thin plate.

14. 14. The cover attachment of claim 13, A cover attachment characterized in that the protrusion is made of metal.

15. A cover attachment according to any one of claims 11 to 14, The cover attachment is characterized in that the protrusion is fixed to the first cover portion.

16. A cover attachment according to claim 15 dependent on claim 14, The cover attachment is characterized in that the protrusion is molded integrally with the first cover part and the second cover part made of resin.

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