EP3141340A1

EP3141340A1 - Grinder

Info

Publication number: EP3141340A1
Application number: EP16187675.0A
Authority: EP
Inventors: Tatsuya Yoshizaki; Yuta IZUTSU
Original assignee: Makita Corp
Current assignee: Makita Corp
Priority date: 2015-09-10
Filing date: 2016-09-07
Publication date: 2017-03-15
Anticipated expiration: 2036-09-07
Also published as: JP6632840B2; JP2017052059A; US20170072533A1; EP3141340B1; CN106514496A

Abstract

A grinder (2) includes a motor (12), a housing that houses the motor (12), a spindle (24) that projects from the housing and is driven by the motor (12), and thereby rotates relative to the housing, and a wheel cover (10) that is disposed on an outer-circumference side of the spindle (24) and is configured to cover a portion of a tool accessory attached to the spindle (24). The grinder (2) also includes a holding device for holding the wheel cover (10) on the housing such that the arrangement and position of the wheel cover (10) around the spindle (24) can be changed but such that the wheel cover (10) is not readily removable from the housing.

Description

TECHNICAL FIELD

The present invention relates to a grinder that performs processing, such as grinding, polishing, cutting, or the like, on a workpiece.

BACKGROUND ART

A grinder comprises a spindle that is rotationally driven by a motor. The spindle protrudes from a housing, in which the motor is housed, and a discoidal (disk-shaped) tool accessory (tip tool) is attached to the tip of the spindle. As a result, the tool accessory is rotated by the rotation of the spindle, and processing of the workpiece can be performed.
A wheel cover, which covers part of the tool accessory, may be provided on an outer-circumference side of the spindle to which the tool accessory is attached, as disclosed, e.g., in Japanese Laid-open Patent Publication numbers 2013-78823 and 2013-226617 .

SUMMARY OF THE INVENTION

In prior art devices, the wheel cover is detachably mounted around a protruding part, in which the spindle protrudes from the housing. Consequently, if the wheel cover is removed from the housing by a user, the processing work is performed on the workpiece with the entire tool accessory (e.g., a cutting blade) is exposed.
Accordingly, it is an object of the present teachings is to disclose a grinder that prevents, or at least discourages, a user from removing the wheel cover and then using the grinder with the wheel cover removed in an unsafe manner.
A grinder according to one aspect of the present teachings comprises: a motor; a housing that houses the motor; and a spindle that projects from the housing and is driven by the motor, and thereby rotates inside the housing.
In addition, a wheel cover is disposed on an outer-circumference side of the spindle projecting from the housing and is designed to cover a portion of a tool accessory attached to the spindle. The wheel cover is held on the housing by one or more holding members, which is (are each) configured as a separate structure from the wheel cover, and the arrangement and position of the wheel cover around the spindle can be changed. The one or more holding members preferably retain or hold the wheel cover on the housing in an undetachable and/or captive manner, or at least in a manner that the wheel cover is not readily or easily removable from the housing, as will be further explained below.
According to such a grinder, to remove the wheel cover from the grinder, it is necessary to remove the holding member(s) from the wheel cover, the housing, and the like, and that removal work is labor-intensive. Consequently, it is possible to discourage or prevent the user from removing the wheel cover and then using the grinder with the wheel cover removed.
In addition, even though the wheel cover is fixed to the housing by using the holding member(s), the arrangement of the wheel cover around the spindle can be changed; consequently the position of the wheel cover, e.g., its rotational position, can be adjusted as appropriate during usage of the grinder, thereby maintaining this ergonomic aspect (usability) of conventional grinders while making the device safer to use.
In such an embodiment, the housing includes a mounting portion, to which the wheel cover is attached, that has a circular-cylinder shape that surrounds the spindle; the wheel cover may comprise a circular-ring-shaped mounting part that is capable of being externally fitted onto the mounting portion of the housing.
Furthermore, in such an embodiment, a slit may be provided in the circular-ring-shaped mounting part of the wheel cover in an outer-circumferential direction of the mounting portion of the housing, and the (each) holding member may comprise a rivet or a screw that is inserted into that slit.
In such a design, the rivet or the screw is inserted into the slit, one end of the rivet or the screw is fixed to the mounting portion of the housing, and a head on the other-end side of the rivet or the screw is made larger than the width of the slit, thereby making it possible to firmly hold (retain) the wheel cover on the housing by using the holding member(s).
Furthermore, in such a design, if the (each) holding member comprises a rivets, then, to remove the wheel cover from the housing, the head of the rivet must be removed using a tool, and that removal work would be extremely labor-intensive. Consequently, such a design further prevents or discourages the removal of the wheel cover.
On the other hand, if the (each) holding members comprises a screws, then the screw could be easily removed if its head has a shape (e.g., a plus (+) shape, a minus (-) shape, or the like) that corresponds to a common tool (e.g., a flat-head screwdriver or a Phillips-head screwdriver). Therefore, in such an embodiment, the head of the screw should preferably be crushed or otherwise deformed, or should be made such that the screw cannot be turned, such as by using an adhesive or the like.
In addition, if the head of the screw is made into a shape that can mate only with a special tool that is not commercially available, then not only is it possible to more effectively discourage or even prevent the removal of the wheel cover, but it becomes possible to remove the screw only by using a special tool. Accordingly, in such a design, the replacement of the wheel cover can be effected by an authorized repair person in a simple manner without damaging the grinder, peripheral members, and the like.
In another embodiment of the present teachings, two or more of the holding members may be distributed over and fixed at a plurality of locations of the outer circumference of the mounting portion of the housing. In this case, the wheel cover can be held on the housing at a plurality of locations using the holding members. Therefore, tilting of the center axis of the wheel cover with respect to the center axis of the mounting portion of the housing can be prevented. Accordingly, work efficiency is improved when the wheel cover is rotated around the spindle in order to adjust the (rotational) position of the wheel cover.
In addition, a tightening member may be provided to tighten and thereby fix the circular-ring-shaped mounting part on the outer circumference of the mounting portion of the housing. The tightening member may be provided on the mounting part of the wheel cover. In such an embodiment, the wheel cover can be positioned with respect to and fixed on the housing by the tightening member. Therefore it is possible to prevent the position of the wheel cover from shifting with respect to the tool accessory during usage of the grinder and to prevent degradation in the usability of the grinder.
Moreover, similar to the above-described grinder, a grinder according to another aspect of the present teachings comprises: a motor; a housing that houses the motor; and a spindle that projects from the housing and is driven by the motor, and thereby rotates inside the housing.
In addition, a wheel cover is provided for covering a portion of a tool accessory attached to the spindle and is disposed on an outer-circumference side of the spindle projecting from the housing. The wheel cover is undetachably held on the housing.
Accordingly, in such a grinder, the wheel cover can no longer be removed from the grinder without destroying the wheel cover or portions thereof, thereby preventing or at least significantly discouraging the user from removing the wheel cover and then using the grinder with the wheel cover removed.
In such an embodiment, if the housing has a mounting portion, on which the wheel cover is attached, that has a circular-cylinder shape that surrounds the spindle and if the wheel cover comprises a circular-ring-shaped mounting part capable of being externally fitted onto the mounting portion of the housing, then the grinder may comprise the following parts.
That is, one of an outer circumference of the mounting portion of the housing and an inner circumference of the mounting part of the wheel cover may have a groove formed along a circumferential direction, and the other one may have a projection or a ridge, which is inserted into the groove and is capable of sliding within the groove, formed thereon.
In this way, the mounting portion of the housing and the mounting part of the wheel cover are coupled by the groove and the projection or the ridge; therefore, the wheel cover can be rotated with respect to the housing in the circumferential direction and cannot move in the center-axis direction.
Consequently, it is possible to adjust the arrangement and position (e.g., rotational position) of the wheel cover around the spindle even though the wheel cover is undetachably held on the housing.
In another embodiment, the outer circumference of the mounting portion of the housing and the inner circumference of the mounting part of the wheel cover may each have corrugated shapes that engage at prescribed rotational-angle positions and thereby are capable of positioning the wheel cover with respect to the housing.
In such an embodiment, it is possible to position the wheel cover at an arbitrary location (rotational position) around the spindle, and thereby to easily adjust and fix the position of the wheel cover. In addition, the mounting part on the wheel cover may be configured in a circular-ring shape with the open ends of a circular ring being coupled together by a fixing member. In such an embodiment, the wheel cover can be removed from the housing by removing the fixing member and uncoupling the open ends. Accordingly, it is possible to replace the wheel cover for maintenance purposes at, for example, a power tool repair shop.
Furthermore, in such an embodiment, for example, a rivet as described above may be used as the fixing member. That is, a rivet cannot be removed in a simple manner using a tool, and therefore the wheel cover can be undetachably held on the housing using the rivot.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view that shows the configuration of a grinder according to a first embodiment.
FIG. 2 is a cross-sectional view in which a mounting part, which mounts a wheel cover on a housing, is sectioned along (through) its slits.
FIG. 3 is a cross-sectional view that shows the state in which the wheel cover has been rotated from the position shown in FIG. 2.
FIG. 4 is an oblique view that shows the external appearance of the wheel cover attached to the grinder.
FIG. 5 is an oblique view that shows the state in which the wheel cover has been rotated from the position shown in FIG. 4.
FIG. 6 is an oblique view that shows the configuration of the entire grinder according to a second embodiment.
FIG. 7 is a cross-sectional view that shows the state wherein the wheel cover and the grinder are sectioned along a center axis of a spindle.
FIG. 8 is an oblique view that shows the configuration of the entire grinder according to a third embodiment.
FIG. 9 is an oblique view that shows the configuration of a wheel cover.
FIG. 10 is a plan view that shows the state of the grinder, viewed from the wheel cover side, from which the wheel cover has been removed.
FIG. 11 is a cross-sectional view taken along line A-A in FIG. 10.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are explained below, with reference to the drawings.

First Embodiment

As shown in FIG. 1, a grinder 2 of the present embodiment principally comprises a motor housing 4, a gear housing 6, a rear cover 8, and a wheel cover 10.
The motor housing 4 is substantially circular-cylindrical and houses a motor 12. A rotary shaft 14 of the motor 12 is disposed such that it protrudes toward the gear housing 6.
The rear cover 8 is provided on one-end side of the motor housing 4 in a center-axis direction and houses a power-supply wiring part 16. A power-supply cord 18, which supplies electric current from an external power supply, and a switch 19, which switches the drive of the grinder 2 ON and OFF, are provided in (as parts of) the power-supply wiring part 16. The power-supply wiring part 16 is electrically connected to the motor 12.
The gear housing 6 is provided on the side of the motor housing 4 opposite the rear cover 8 and houses a first bevel gear 20, a second bevel gear 22, a spindle 24, bearings 26, 28, and the like.
The first bevel gear 20 is fixed to the rotary shaft 14 of the motor 12 inside the gear housing 6. The second bevel gear 22, the spindle 24, and the bearings 26, 28 are provided integrally with an inner housing 30, which is configured as a structure separate from the gear housing 6, and are housed inside the gear housing 6 by virtue of the inner housing 30 being mated to and fixed inside the gear housing 6.
Furthermore, the inner housing 30 is fixed to the gear housing 6 by passing headed male screws 29 (refer to FIG. 4 and FIG. 5), from the inner housing 30 side, through screw holes provided in the same axial direction as the spindle 24 at four locations of the inner housing 30 and four locations of the gear housing 6 around the spindle 24 and then screwing the headed male screws 29 into female threads formed in the screw holes on the gear housing 6 side.
The spindle 24 is rotatably provided via a bearing 26 in the inner housing 30. The inner housing 30 has a circular-cylinder shape that is coaxial with the center axis of the spindle 24 and is fixed inside the gear housing 6 such that the spindle 24 is orthogonal to the rotary shaft 14 of the motor 12.
The second bevel gear 22 is fixed to the spindle 24 and meshes with the first bevel gear 20 inside the gear housing 6, and thereby the rotational output of the motor 12 is converted to a rotational force around the axis of the spindle 24.
One end of the spindle 24 is rotatably supported by the gear housing 6 via the bearing 28, and the other end of the spindle 24 protrudes externally from the inner housing 30 (in other words, from the gear housing 6).
An inner flange 32 for positioning and fixing a discoidal tool accessory (not shown) is provided on the portion of the spindle 24 that protrudes from the gear housing 6. In addition, a threaded portion 25, onto which a lock nut 34 is screwed, is formed on an outer-circumferential portion of the spindle 24 that is closer to the tip than the inner flange 32. The lock nut 34 is for holding the tool accessory between the lock nut 34 and the inner flange 32.
In the grinder 2 configured in this manner, when the switch 19 changes to the ON state, the motor 12 rotates and the rotational output thereof is transmitted to the spindle 24 via a gear mechanism (the first bevel gear 20 and the second bevel gear 22) inside the gear housing 6.
Consequently, if the tool accessory is fixed beforehand to the spindle via the lock nut 34, then the tool accessory rotates and thereby work, such as grinding, polishing, and cutting, can be performed. Furthermore, a grinding stone, a cutting stone, a wire brush, and the like are representative, non-limiting examples of a tool accessory that may be used with the grinder 2 in this manner.
In addition, a fan 15, which draws in outside air from an inlet hole of the rear cover 8 and exhausts air via an exhaust hole 7 provided in the gear housing 6, is provided on the rotary shaft of the motor 12. The rotation of the fan 15 causes outside air to pass around the motor 12, thereby cooling the motor 12.
The wheel cover 10 is for protecting the user from flying debris of the workpiece, the tool accessory, or the like generated during an operation, such as grinding, polishing, cutting, or the like. Consequently, the wheel cover 10 is formed as substantially a semicircle such that the portion (more particularly, approximately half) of the tool accessory that is fixed to the spindle 24 is covered from the gear housing 6 side.
The wheel cover 10 is fixed to the inner housing 30 at the portion where the spindle 24 protrudes. This fixed structure is discussed in detail below.
As shown in FIG. 2 and FIG. 3, on the inner housing 30, a mounting portion 40 for mounting the wheel cover 10 has a circular-cylinder shape such that it is coaxial with the center axis of the spindle 24 and surrounds the spindle 24.
In addition, as shown in FIG. 1 to FIG. 5, on the wheel cover 10, a semicircular wall part 50, which makes contact with an outer circumference of the mounting portion 40 of the inner housing 30 and is capable of pivoting around the spindle 24, extends vertically upward from a center portion of a semicircular plate surface, which is disposed so as to oppose the tool accessory.
Furthermore, a circular-ring-shaped mounting part 52 is joined to the wall part 50 such that the mounting part 52 surrounds the entire outer-circumferential area of the mounting portion 40 of the inner housing 30.
The wheel cover 10 is composed of a metal plate, the main element of which is iron, and the wall part 50 is formed integrally with the wheel cover 10 by press molding or the like. In addition, the mounting part 52 is composed of an elongated metal plate, the main element of which is iron, and is formed into a circular-ring shape by press molding or the like. Furthermore, open ends of the circular ring of the mounting part 52 are bent toward the outer side of the circular ring such that the mounting part 52 can be tightened in a radial direction by a tightening member 58 (refer to FIG. 2, FIG. 3, and the FIG. 5). Furthermore, in the present embodiment, the tightening member 58 comprises a headed male screw 58A and a nut 58B.
The mounting part 52 is joined to the wheel cover 10 by welding or the like such that the mounting part 52 surrounds the wall part 50 of the wheel cover 10. Furthermore, elongated slits 54A, 54B (identified as merely 54 in Fig. 1) are formed in the mounting part 52 and in the wall part 50 of the wheel cover 10, to which the mounting part 52 is joined, along a circumferential direction of the circular ring of the mounting part 52 such that the slits 54A, 54B pass through from the outer side to the inner side of the circular ring.
The slits 54A, 54B are formed in two areas that extend from the open-end sides of the circular ring of the mounting part 52 to the side opposite the open ends such that the center axis of the circular ring is interposed therebetween, as shown by arrows in FIG. 2 and FIG. 3.
Headed male screws 56A, 56B, the heads of which are larger than the widths of the slits 54A, 54B, are inserted through the two slits 54A, 54B, respectively, from the outer side of the mounting part 52. Furthermore, the male screws 56A, 56B are fixed in female threads 57A, 57B, respectively, provided in the mounting portion 40 of the inner housing 30. The headed male screws 56A, 56B may alternatively be formed as bolts with heads wider than the narrow width of the slits or as rods with heads wider than the narrow width of the slits.
Furthermore, in the mounting portion 40 of the inner housing 30, the female threads 57A, 57B, in which the male screws 56A, 56B are fixed, are formed at locations substantially opposing one another and sandwiching the center axis of the mounting portion 40.
As a result, as can be understood from FIG. 2 and FIG. 3 or from FIG. 4 and FIG. 5, the wheel cover 10 is capable of pivoting around the spindle 24 by the rotational-angle range (about 180°) in which the slits 54A, 54B are formed.
Thus, in the grinder 2 of the present embodiment, the circular-ring shaped mounting part 52, which is integrally assembled with the wheel cover 10, is mated to the mounting portion 40 of the inner housing 30, from which the spindle 24 protrudes.
Furthermore, the male screws 56A, 56B pass through the slits 54A, 54B formed in the mounting part 52 and are fixed in the female threads 57A, 57B of the mounting portion 40; thereby, the wheel cover 10 is held on the inner housing 30.
According to the grinder 2 of the present embodiment, to remove the wheel cover 10 from the grinder 2, it is necessary to remove the male screws 56A, 56B, which are holding members, from the mounting portion 40 of the inner housing 30, and that removal work is labor-intensive. Consequently, it is possible to prevent the user from removing the wheel over 10 and then using the grinder 2 with the wheel cover 10 removed.
In addition, the mounting portion 40 of the inner housing 30 is a circular cylinder that is coaxial with the center axis of the spindle 24, and consequently the wheel cover 10 can pivot around the spindle 24 although the pivotable range is limited by the length of the slits 54A, 54B in the circumferential direction.
Consequently, the user can arbitrarily set the arrangement and position of the wheel cover 10 around the spindle 24-in other words, the arrangement and position of the area covered by the tool accessory fixed to the spindle 24-and therefore the ergonomics or usability of the grinder 2 is (are) not diminished.
Furthermore, in the wheel cover 10, the open ends of the circular ring of the mounting part 52 are bent toward the outer side of the circular ring, the male screw 58A, which (together with the nut 58B) constitutes the tightening member 58, passes through those bent portions. By screwing it into the nut 58B, the male screw 58A can tighten the wheel cover 10 in the radial direction.
Consequently, after the user sets the arrangement and (rotational) position of the wheel cover 10 around the spindle 24, the user can position and fix the wheel cover 10 around the spindle 24 by tightening the mounting part 52 of the wheel cover 10 in the radial direction via the tightening member 58.
Thereby, it is possible to prevent the position of the wheel cover 10 from shifting with respect to the tool accessory when the grinder 2 is being used, which would be disadvantageous.
In addition, the male screws 56A, 56B, which serve as the holding members, are fixed (screw-fastened) at two locations that substantially divide the outer circumference of the mounting portion 40 of the inner housing 30 into two, and the two slits 54A, 54B, which are for the male screws 56A, 56B to be inserted into, are formed in the mounting part 52 of the wheel cover 10.
Consequently, according to the grinder 2 of the present embodiment, the wheel cover 10 can be held on the inner housing 30 by the male screws 56A, 56B such that the center axis of the inner housing 30 (and in turn, the spindle 24) and the center axis of the wheel cover 10 substantially coincide.
Accordingly, when the rotational position of the wheel cover 10 is being adjusted by pivoting it around the spindle 24, it is possible to prevent the center axis of the wheel cover 10 from tilting with respect to the center axis of the mounting portion 40 of the inner housing 30 and thereby making the positional adjustment easy to perform without disadvantageous results.
Furthermore, in the present embodiment, because the headed male screws 56A, 56B, which serve as the holding members, are used, the wheel cover 10 would be easy to remove from the grinder if the heads of the male screws 56A, 56B were to have a shape that corresponds to a common tool (e.g., a flat screwdriver or a Phillips-head screwdriver).
Consequently, the heads of the male screws 56A, 56B are instead preferably shaped such that the male screws 56A, 56B can mate only with a special tool that is not commercially available and should be made such that the male screws 56A, 56B cannot be unscrewed from the inner housing 30 in a simple manner.
In addition, to that end, the male screws 56A, 56B may be bonded to the inner housing 30 by using, for example, a screw-fixing adhesive. In addition, the heads of the male screws 56A, 56B may be crushed or otherwise deformed so that the male screws 56A, 56B cannot be unscrewed from the inner housing 30 using a tool.

Second Embodiment

As shown in FIG. 6 and FIG. 7, the grinder 2 of the present embodiment has the same basic configuration as the first embodiment but differs from the first embodiment in that rivets 60A, 60B (in the drawings, only the rivet 60A is shown), which serve as fixing members, are substituted for the male screws 56A, 56B.
Furthermore, in FIGS. 6, 7, the structural elements, other than the rivets 60A, 60B, are the same as those in the first embodiment; structural elements the same as those in the first embodiment are assigned the same reference numerals, and explanations thereof are omitted.
As shown in FIG. 6 and FIG. 7, in the grinder 2 of the present embodiment, the rivets 60A, 60B, instead of the male screws 56A, 56B, are inserted through the slits 54A, 54B formed in the wall part 50 of the wheel cover 10 and in the mounting part 52.
Furthermore, as shown in FIG. 7, instead of the female threads 57A, 57B, the rivets 60A, 60B are driven into and mated in holes 61 A, 61B (in the drawings, only the hole 61A is shown) formed in the mounting portion 40 of the inner housing 30. As a result, the wheel cover 10 is held on the inner housing 30 so as to be pivotable via the rivets 60A, 60B.
Thereby, the grinder 2 of the present embodiment can likewise achieve the same effects as those of the first embodiment. In addition, by virtue of being driven into the holes 61 A, 61B, the rivets 60A, 60B are more difficult to remove as compared with the male screws 56A, 56B, and therefore it is possible to more satisfactorily prevent the wheel cover 10 from being removed from the grinder 2.

Third Embodiment

As shown in FIG. 8 to FIG. 11, the grinder 2 of the present embodiment has the same basic configuration as the first and second embodiments, but differs from the above-mentioned embodiments in the wall part 50 of the wheel cover 10, the mounting portion 40 of the inner housing 30, and a tightening member 62.
Accordingly, in the present embodiment, in FIG. 8 to FIG. 11, structural elements the same as those of the above-mentioned embodiments are assigned the same reference numerals, and explanations thereof are omitted while points of difference are explained.
As shown in FIG. 8 and FIG. 10, the outer-circumferential surface of the mounting portion 40, on which the wheel cover 10 in the inner housing 30 is attached, is a corrugated shape having convex and concave shapes formed at prescribed rotational angles around the center axis of the inner housing 30 (in other words, the spindle 24).
In addition, as shown in FIG. 9, the wheel cover 10 includes the wall part 50, which makes contact with the mounting portion 40 of the inner housing 30, that likewise has a corrugated shape that corresponds to the outer-circumferential surface of the mounting portion 40.
Furthermore, as in the above-mentioned embodiments, the ring-shaped mounting part 52 is joined, from the outer side, to the wall part 50 of the wheel cover 10 by welding or the like. Consequently, substantially half of an inner-circumferential surface of the mounting part 52 assumes a corrugated shape that corresponds to the outer-circumferential surface of the mounting portion 40 of the inner housing 30.
Accordingly, if the wheel cover 10 is pivoted around the spindle 24 in the state in which the wheel cover 10 is attached to the inner housing 30, then the wheel cover 10 becomes positioned at an arbitrary rotational-angle position at which the corrugations formed on the outer-circumferential surface of the mounting portion 40 and on the inner-circumferential surface of the mounting part 52 overlap (engage) one another.
In addition, as shown in FIG. 9, projections 51 extend vertically upward on the wall part 50 of the wheel cover 10 on both end sides in the circumferential direction of the semicircular shape. Furthermore, FIG. 9 shows the state of the wheel cover 10 before the mounting part 52 is joined to the wall part 50 by welding or the like.
On the other hand, as shown in FIG. 11, a groove 42 is formed substantially around the entire outer-circumferential surface of the mounting portion 40 of the inner housing 30. The inner-circumferential surface of the wall part 50 of the wheel cover 10 makes contact with the outer-circumferential surface of the mounting portion 40.
When the wheel cover 10 is to be mounted to the mounting portion 40 of the inner housing 30 by using the mounting part 52, the projections 51 are inserted into the groove 42 and can be slid along the groove 42 when the wheel cover 10 is pivoted around the spindle 24.
Consequently, once the wheel cover 10 is attached to the inner housing 30, the diameter of the mounting part 52 widens and thereby the wheel cover 10 cannot be moved in the center-axis direction of the spindle 24 and can not be removed from the inner housing 30 unless the projections 51 are taken out of the groove 42.
Furthermore, in the present embodiment, a rivet is used as the tightening member 62 that couples the open ends of the mounting part 52 such that the wheel cover 10 cannot be removed from the inner housing 30 (in other words, so that the wheel cover 10 is undetachable). This rivet is a type wherein the rivet is passed through the holes in the open ends, the rivet is upset on both sides using a tool, and thereby locking heads are formed on both sides of the holes.
Consequently, after the mounting part 52 is fixed by tightening the mounting part 52 around the mounting portion 40 of the inner housing 30 by using the tightening member 62, which is a rivet, the wheel cover 10 can no longer be removed from the grinder 2.
In addition, the wheel cover 10 is capable of pivoting around the spindle 24 by sliding the projections 51, which extend upward on the wall part 50 that constitutes part of the inner-wall surface of the mounting part 52, along the groove 42 formed on the outer-circumferential surface of the mounting portion 40 of the inner housing 30.
Furthermore, that pivot position is located at any arbitrary rotational-angle position at which the corrugation formed on the outer-circumferential surface of the mounting portion 40 of the inner housing 30 and the corrugation formed on the wall part 50, which is the inner-circumferential surface of the mounting part 52, overlap (engage) one another. Accordingly, in the present embodiment, the wheel cover 10 can be easily positioned around the spindle 24.
Representative, non-limiting embodiments of the present teachings are explained above, but the present invention is not limited to the above-mentioned embodiments and it is understood that variations and modifications may be effected without departing from the spirit and scope of the invention.
For example, the above-mentioned embodiments explain that the wheel cover 10 is held on the inner housing 30, in which the spindle 24 is provided, but the wheel cover 10 may be held on the gear housing 6, in which the inner housing 30 is housed.
In addition, grinders according to the present teachings may be configured such that the gear housing 6 is integrated with the inner housing 30. In such an embodiment, the spindle 24, the first bevel gear 20, the second bevel gear 22, the bearings 26, 28, and the like are all provided directly in the gear housing 6.
Moreover, in the first and second embodiments, the wheel cover 10 is prevented from being removed from the grinder 2 while permitting the pivoting of the wheel cover 10 around the spindle 24 by providing the slits 54A, 54B and by the male screws 56A, 56B or by providing the rivets 60A, 60B inserted into the slits 54A, 54B. In addition, the third embodiment achieves the same effects by using the groove 42 and the projections 51.
On the other hand, the same effects can be achieved even if, for example, the ring-shaped mounting part 52 of the wheel cover 10 is externally fitted on the mounting portion of the housing of the grinder 2 and then the diameter of the open ends of the ring shape of the mounting portion are widened.
In addition, the first and second embodiments explained that the number of the male screws 56A, 56B or the rivets 60A, 60B, which serve as the holding members, is two, but the number may be one or may be three or more. In addition, in the third embodiment, the number of the projections 51 inserted into the groove 42 may be three or more, and may be ridges instead of projections.
In addition, each of the above-mentioned embodiments explain that the mounting part 52 of the wheel cover 10 is integrally joined to the wall part 50 of the wheel cover 10, but the mounting part 52 may be integrally formed together with the wheel cover 10.

Other Embodiments

The first embodiment to the third embodiment are explained above, but the grinder of the present disclosure are not limited to the above-mentioned embodiments, and various other embodiments can be adopted. These other embodiments include, but are not limited to:

1. A grinder, comprising:
- a motor;
- a housing that houses the motor;
- a spindle that projects from the housing and is driven by the motor and thereby rotates relative to the housing; and
- a wheel cover disposed on an outer-circumference side of the spindle projecting from the housing and being configured to cover a portion of a tool accessory attached to the spindle and to pivot relative to the spindle;
wherein the wheel cover is configured such that it is undetachably held on the housing.
2. The grinder according to the above-described embodiment 1, wherein:
- the housing includes a mounting portion, to which the wheel cover is attached, that has a circular-cylinder shape and surrounds the spindle;
- the wheel cover comprises a circular-ring-shaped mounting part configured to be externally fitted onto the mounting portion of the housing; and
- one of an outer circumference of the mounting portion of the housing and an inner circumference of the mounting part of the wheel cover has a groove that is formed along a circumferential direction, and the other one has a projection or a ridge, which is inserted into the groove and is capable of sliding within the groove.
3. The grinder according to the above-described embodiment 2, wherein:
- the outer circumference of the mounting portion of the housing and the inner circumference of the mounting part of the wheel cover each have corrugated shapes that engage at prescribed rotational-angle positions and thereby are capable of positioning the wheel cover with respect to the housing.
4. The grinder according to the above-described embodiment 2, wherein:
- the mounting part on the wheel cover is configured in a circular-ring shape such that open ends of a circular ring are coupled together by a fixing member.
5. The grinder according to the above-described embodiment 1, wherein:
- the housing includes a mounting portion, to which the wheel cover is attached, that has a circular-cylinder shape and that surrounds the spindle;
- the wheel cover is configured to be externally fitted onto the mounting portion of the housing and comprises a circular-ring-shaped mounting part having an outwardly facing circumferential slit; and
- a rivet or a screw extends from the mounting portion into the slit of the mounting part of the wheel cover, one end of the rivet or screw being fixed to the mounting portion of the housing and the other end of the rivet or screw having a head larger than a width of the slit.
6. The grinder according to the above-described embodiment 1, further comprising at least one rod projecting from the housing and extending through at least one circumferential slit in the wheel cover.
7. A grinder, comprising:
- a housing including a cylindrical mounting portion;
- a motor in the housing;
- a spindle operatively connected to the motor, the spindle projecting from the cylindrical mounting portion and being configured to be driven by the motor and to rotate relative to the housing;
- a wheel cover including a ring-shaped mounting part mounted on the cylindrical mounting portion and a covering part radially spaced from and extending partially around the spindle, the covering part being configured to cover a portion of a tool accessory attached to the spindle, the mounting portion including a first circumferential slit having first and second ends; and
- a first rod projecting from the mounting portion and extending through the first circumferential slit, the first rod having a head larger than an axial width of the first circumferential slit,
the wheel cover being shiftable between a first portion in which the first rod contacts the first end of the first circumferential slit and a second position in which the first rod contacts a second end of the first circumferential slit.
8. The grinder according to the above-described embodiment 7, wherein:
- the mounting portion includes a second circumferential slit and
- the grinder includes a second rod projecting from the mounting portion through the second circumferential slit, the second rod having a head larger than a width of the second circumferential slit.
9. The grinder according to the above-described embodiment 8, wherein the wheel cover is undetachably held on the housing.
10. The grinder according to the above-described embodiment 9, wherein the wheel cover is captively held on the housing.

Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above and below may be utilized separately or in conjunction with other features and teachings to provide improved power tools, such as grinders.
Moreover, combinations of features and steps disclosed in the above detailed description, as well as in the below additional examples, may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.
All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

EXPLANATION OF THE REFERENCE NUMBERS

2: Grinder
4: Motor housing
6: Gear housing
7: Exhaust hole
8: Rear cover
10: Wheel cover
12: Motor
14: Rotary shaft
15: Fan
16: Power-supply wiring part
18: Power-supply cord
19: Switch
20: First bevel gear
22: Second bevel gear
24: Spindle
25: Threaded portion
26,28: Bearings
30: Inner housing
32: Inner flange
34: Lock nut
40: Mounting portion
42: Groove
50: Wall part
51: Projection
52: Mounting part
54A, 54B: Slits
56A, 56B: Male screws
57A, 57B: Female threads
58, 62: Tightening members
60A: Rivet

Claims

A grinder (2), comprising:
a motor (12);

a housing (4) that houses the motor (12);

a spindle (24) that projects from the housing (4) and is driven by the motor (12), and thereby rotates relative to the housing (4);

a wheel cover (10) that is disposed on an outer-circumference side of the spindle (24) projecting from the housing (4) and that is configured to cover a portion of a tool accessory attached to the spindle (24); and

means for holding the wheel cover (10) on the housing (4);
wherein the wheel cover (10) and the holding means (56A, 56B) are configured such that, in the state wherein the wheel cover (10) is held on the housing (4) by the holding means (56A, 56B), the arrangement and position of the wheel cover (10) around the spindle (24) can be changed.
The grinder (2) according to claim 1, wherein the holding means (56A, 56B) comprises at least one holding member configured as a separate structure from the wheel cover (10), the at least one holding member being configured to hold the wheel cover (10) on the housing (4).
The grinder (2) according to claim 2, wherein:
the housing (4) includes a mounting portion (52), to which the wheel cover (10) is attached, that has a circular-cylinder shape and that surrounds the spindle (24);

the wheel cover (10) is configured to be externally fitted onto the mounting portion (52) of the housing (4) and comprises a circular-ring-shaped mounting part, the mounting part including an outwardly facing circumferential slit; and

the at least one the holding member comprises a rivet or a screw extending into the slit of the mounting part of the wheel cover (10), one end of the rivet or screw being fixed to the mounting portion (52) of the housing (4) and the other end of the rivet or screw having a head larger than a width of the slit.
The grinder (2) according to claim 3, wherein:
the at least one holding member comprises a plurality of holding members that are distributed over, and fixed at, a plurality of locations of the outer circumference of the mounting portion (52) of the housing (4).
The grinder (2) according to claim 3, wherein:
the wheel cover (10) includes a tightening member on the mounting part configured to tighten and thereby fix the mounting part on the outer circumference of the mounting portion (52) of the housing (4).
The grinder (2) according to claim 1, wherein:
the housing (4) includes a mounting portion (52), to which the wheel cover (10) is attached, that has a circular-cylinder shape that surrounds the spindle (24);

the wheel cover (10) comprises a circular-ring-shaped mounting part configured to be externally fitted onto the mounting portion (52) of the housing (4); and

the holding means (56A, 56B) comprise a circumferential groove formed on one of an outer circumference of the mounting portion (52) of the housing (4) and an inner circumference of the mounting part of the wheel cover (10) and a projection or ridge on the other one of the mounting portion (52) and the mounting part, the projection or ridge extending into the groove and being configured to slide within the groove.
The grinder (2) according to claim 1, wherein:
an outer circumference of a mounting portion (52) of the housing (4) and an inner circumference of a mounting part of the wheel cover (10) each have corrugated shapes that engage at prescribed rotational-angle positions and thereby are capable of positioning the wheel cover (10) with respect to the housing (4).
The grinder (2) according to claim 2, wherein the holding means (56A, 56B) undetachably holds the wheel cover (10) on the housing (4).
The grinder (2) according to claim 5, wherein the holding means (56A, 56B) undetachably holds the wheel cover (10) on the housing (4).