EP2505308A1

EP2505308A1 - Power tool

Info

Publication number: EP2505308A1
Application number: EP12157709A
Authority: EP
Inventors: Hideharu Muto; Shin Nakamura; Kenichi Tabushi
Original assignee: Makita Corp
Current assignee: Makita Corp
Priority date: 2011-03-31
Filing date: 2012-03-01
Publication date: 2012-10-03
Also published as: US20120252328A1; RU2012112407A; CN102729143A; JP2012213820A

Abstract

In a power tool 1 in which a disc-shaped tool is attached to a spindle (16) that protrudes from a housing (10, 15) in which a motor M is housed. A dust-collecting cover (20) provided on the housing (10, 15) for covering the disc-shaped tool has a tool insertion opening (24B). A rotation stopping tool (25) that stops rotation of the spindle (16) can be inserted into the dust-collecting cover (20) through the tool insertion opening (24B). The duct-collecting cover (20) is provided with a rubber ring (26) that blocks the tool insertion opening such that the tool insertion opening can be opened and closed as desired.

Description

BACKGROUND OF INVENTION

TECHNICAL FIELD

The present invention relates to a power tool including a dust-collecting cover that covers a disc-shaped tool attached to a spindle, and collects dust produced when a workpiece is machined.

BACKGROUND ART

A grinder disclosed in Japanese Patent Application Publication No. 2011-56641 includes a spindle that is rotated by a motor housed in a housing, a disc-shaped grinding tool attached to the spindle, and a dust-collecting cover that covers the periphery of the grinding tool. Generally, the grinder grinds a workpiece by moving the rotating grinding tool on the workpiece while keeping the grinding tool in contact with the workpiece. Dust produced during grinding is collected in the dust-collecting cover, and then discharged from a dust-collecting tube that communicates with the interior of the dust-collecting cover, into a dust collector, via a suction hose.
In a power tool as represented by the above-described grinder, the dust-collecting cover has a tool insertion opening through which a rotation stopping tool, such as a spanner, can be inserted into the opening of the cover. When a lock mechanism for stopping rotation of the spindle fails, rotation of the spindle can be stopped by means of the rotation stopping tool inserted through the opening formed on the cover. However, in the dust-collecting cover having the tool insertion opening, the inside and outside of the dust-collecting cover communicate with each other via the tool insertion opening, and the air tightness within the dust-collecting cover is reduced. Accordingly, efficiency of dust collection in the dust-collecting cover is reduced.
On the other hand, if the tool insertion opening is closed all the time so as to ensure air tightness, as the rotation stopping tool cannot be inserted into the dust-collecting cover, the spindle does not stop rotating when the lock mechanism for the spindle fails.

SUMMARY OF THE INVENTION

This invention is proposed in view of the above situation, and it is an object of the present invention to provide a power tool in which dust is collected in a dust-collecting cover with enhanced efficiency, and rotation of a spindle can be stopped using a rotation stopping tool.
According to a first aspect of the present invention, there is provided a power tool which includes a housing, a motor housed in the housing, a spindle that protrudes from the housing, a disc-shaped tool attached to the spindle, a dust-collecting cover that is provided on the housing, and covers the disc-shaped tool, and a tool insertion opening that is formed in the dust-collecting cover, and enables a rotation stopping tool that stops rotation of the spindle to be inserted into the dust-collecting cover. In the power tool, the dust-collecting cover is provided with an opening and closing member that blocks the tool insertion opening such that the tool insertion opening can be opened and closed as desired.
In the power tool according to a second aspect of the present invention, in the first aspect of the present invention, the opening and closing member may be a ring-shaped rubber member that is mounted on the dust-collecting cover and blocks the tool insertion opening.
In the power tool according to the first aspect of the present invention, the opening and closing member blocks the tool insertion opening formed in the dust-collecting cover, and therefore, the air tightness of the dust-collecting cover is improved. Accordingly, the efficiency of dust collection in the dust-collecting cover can be enhanced. If the tool insertion opening is rendered open to the dust-collecting cover, using the opening and closing member, the rotation stopping tool can be inserted into the dust-collecting cover, through the opened tool insertion opening, so as to stop rotation of the spindle.
When the tool insertion opening is blocked by the ring-shaped rubber member, the air tightness of the dust-collecting cover is improved, and the efficiency of dust collection in the dust-collecting cover can be enhanced. Further, when the rubber member is rolled up, the tool insertion opening of the dust-collecting cover appears, and the rotation stopping tool can be inserted into the dust-collecting cover through the tool insertion opening, so as to stop rotation of the spindle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG 1 is a side cross-sectional view of a disc grinder as one embodiment of the present invention.
FIG 2 is a plan view of a dust-collecting cover included in the disc grinder.
FIG 3 is a view explaining the time when rotation of a spindle of the disc grinder is stopped.

DETAILED DESCRIPTION OF THE EMBODIMENT

One embodiment of the present invention will be described with reference to FIG 1 through FIG 3. A disc grinder 1 shown in FIG 1 includes a housing 10 and a dust-collecting cover 20. The housing 10 consists of a motor housing 11 and a gear housing 15. The disc grinder 1 is one example of power tool of the present invention.
The motor housing 11 is formed in a cylindrical shape, and a motor M is housed in the motor housing 11. A rotary shaft 12 of the motor M is rotatably supported in the motor housing 11 via a bearing 13, and a first bevel gear 14 is provided at a distal end of the rotary shaft 12.
The gear housing 15 is mounted to the front (the left-hand side in FIG 1) of the motor housing 11, and the rotary shaft 12 supported in the motor housing 11 protrudes into the gear housing 15. In addition, a spindle 16 is rotatably supported in the gear housing 15 via bearings 17, 18, to extend in a direction perpendicular to the rotary shaft 12. A second bevel gear 19 is mounted on an upper portion of the spindle 16. With the first bevel gear 14 engaging with the second bevel gear 19, rotation of the rotary shaft 12 is transmitted to the spindle 16. The lower end of the spindle 16 protrudes downwardly of the gear housing 15, and an external threaded portion 16A is formed on an outer circumferential surface of a lower end portion of the spindle 16. In the disc grinder 1, a disc-shaped grinding tool (not shown) is sandwiched between an inner flange and a lock nut screwed on the external threaded portion 16A, and is thus attached to the spindle 16. The disc-shaped grinding tool is one example of disc-shaped tool of the present invention.
As shown in FIG 1 and FIG 2, the dust-collecting cover 20 includes a main cover 21, an auxiliary cover 22, a plate 23, a holder portion 24, and a rubber ring 26. The main cover 21 and the auxiliary cover 23 are formed of resin, and the main cover 21 is provided at its upper surface with an insert hole 21A through which the spindle 16 can be inserted. The auxiliary cover 22 is detachably or removably attached to the main cover 21. In a condition where the auxiliary cover 22 is attached to the main cover 21, the dust-collecting cover 20 assumes a generally bowl-like shape that has a larger diameter than the disc-shaped grinding tool and is open downwards, and surrounds the periphery of the grinding tool. A dust-collecting tube 21B that communicates with the interior of the main cover 21 is provided on the outer surface of the main cover 21. A dust collector can be connected to the dust-collecting tube 21B via a suction hose.
The plate 23 is made of metal, and is fixed to the upper surface of the main cover 21 by means of four screws 23A. The plate 23 is formed with an opening 23B that communicates with the insert hole 21A of the main cover 21. The holder portion 24, which is made of metal and has an annular shape that is concentric with the opening 23B, is formed integrally with the upper surface of the plate 23. By fitting the holder portion 24 on a lower end portion of the gear housing 15 and fastening it with a screw 24A, the duct-collecting cover 20 is coupled to the gear housing 15.
As shown in FIG 1 and FIG 3, a tool insertion slot 24B is formed in a base portion of the holder portion 24 in the vicinity of the boundary between the plate 23 and the holder portion 24. The tool insertion slot 24B is used for inserting a spanner 25 into the dust-collecting cover 20. Further, the rubber ring 26, which has a flange portion 26A (see FIG 3) provided at its lower end portion and extending in radial directions, is fitted along the outer circumferential surface of the above-mentioned base portion. As shown in FIG 1, the rubber ring 26, which is in close contact with the outer circumferential surface of the base portion, normally blocks the tool insertion slot 24B, and the flange portion 26A, which is in close contact with the upper surface of the plate 23, closes a clearance between the rubber ring 26 and the upper surface. The rubber ring 26 is one example of ring-shaped rubber member of the present invention.
Next, the operation of the disc grinder 1 will be described. When grinding a workpiece with the disc grinder 1, the operator holds the motor housing 11, and turns a switch ON so as to drive the motor M to operate the dust collector. The grinding tool that rotates with the motor M thus driven is moved on a worked surface of the workpiece while being kept in contact with the worked surface, so as to grind the worked surface. Dust produced during grinding of the worked surface is sucked and collected from the duct-collecting tube 21B into the dust collector via the suction hose. At this time, the rubber ring 26 blocks the tool insertion slot 24B, and the flange portion 26A closes the clearance between the rubber ring 26 and the upper surface of the plate 23; therefore, the inside and outside of the dust-collecting cover 20 do not communicate with each other, and the dust-collecting cover 20 is sealed with improved tightness. Accordingly, the dust is prevented from scattering out of the dust-collecting cover 20, and the dust-collecting efficiency of the dust-collecting cover 20 is enhanced.
In the meantime, if a lock mechanism for stopping rotation of the spindle 16 fails when a worn grinding tool is to be replaced by a new one, for example, the rotation of the spindle 16 needs to be stopped by a spanner 25. In this case, the rubber ring 26 is rolled up so that the tool insertion slot 24B is open to a surface of the dust-collecting cover 20, as shown in FIG 3. Then, as shown in FIG 3, the spanner 25 is inserted into the dust-collecting cover 20 through the tool insertion slot 24B, to be engaged with a chamfered portion formed on the spindle 16, so as to stop rotation of the spindle 16. The spanner 25 is one example of rotation stopping tool of the present invention.

In the disc grinder 1 of this embodiment, the rubber ring 26 blocks the tool insertion slot 24B, so that the dust-collecting cover 20 is sealed with improved tightness. As a result, the efficiency of dust collection in the dust-collecting cover 20 can be enhanced. Also, by rolling up the rubber ring 26, it is possible to open the tool insertion slot 24B to the dust-collecting cover 20. Then it becomes possible to insert the spanner 25 into the dust-collecting cover 20 through the tool insertion slot 24B, and stop rotation of the spindle 16 with the spanner 25.
The present invention is not limited to the above-described embodiment, but may be embodied by changing a part of the construction as needed, without departing from the principle of the invention. For example, the rubber ring 26 may be replaced by an O ring made of rubber, and the O ring may be fitted along the outer circumferential surface of the above-mentioned base portion, so that the O ring blocks the tool insertion slot 24B.
Unlike the above-described embodiment, an opening and closing plate that is rotatable in the vertical direction via a hinge member, for example, may be mounted on the holder portion 24, and the tool insertion slot 24B may be blocked by the opening and closing plate, such that the tool insertion slot 24B can be opened or closed as desired. With this arrangement, dust can be collected in the dust-collecting cover 20 with enhanced efficiency, and the rotation of the spindle 16 can be stopped by the spanner 25, as in the above-described embodiment.
As a further example, a rubber magnet that is detachably attached to the holder portion 24 may be provided, in place of the above-described rubber ring 26, for blocking the tool insertion slot 24B such that the tool insertion slot 24B can be opened or closed as desired. In this case, too, dust can be collected in the dust-collecting cover 20 with enhanced efficiency, and the rotation of the spindle 16 can be stopped by the spanner 25, as in the above-described embodiment. The opening and closing plate and the rubber magnet are examples of opening and closing member of the present invention. While the present invention is applied to the disc grinder in the above-described embodiment, the application is not limited to this example, but the present invention may also be applied to a power tool, such as a sander or a cutter having a dust-collecting cover.
It is explicitly stated that 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 disclosure as well as for the purpose of restricting the claimed invention independent of the composition of the features in the embodiments and/or the claims. It is explicitly stated that all value ranges or indications of groups of entities disclose every possible intermediate value or intermediate entity for the purpose of original disclosure as well as for the purpose of restricting the claimed invention, in particular as limits of value ranges.

Claims

A power tool (1) in which a spindle (16) that protrudes from a housing (10, 15), in which a motor (M) is housed, is adapted to have a disc-shaped tool attached thereto, and a dust-collecting cover (20) that covers the disc-shaped tool is provided on the housing (10, 15), while the dust-collecting cover (20) is formed with a tool insertion opening (24B) through which a rotation stopping tool (25) that is adapted to stop rotation of the spindle (16) can be inserted into the dust-collecting cover (20), characterized in that
the dust-collecting cover (20) is provided with an opening and closing member that is adapted to block the tool insertion opening (24B) such that the tool insertion opening can be opened and closed as desired.
The power tool (1) according to claim 1, wherein the opening and closing member is a ring-shaped rubber member (26) that is mounted on the dust-collecting cover (20) and adapted to block the tool insertion opening (24B).
The power tool (1) according to claim 1 or 2, wherein the dust-collecting cover (20) includes a main cover (21) having an insert hole (21A) through which the spindle (16) can be inserted, a plate (23) fixed to an upper surface of the main cover (21) and formed with an opening (23B) that communicates with the insert hole (21A), and a holder portion (24) having an annular shape that is concentric with the opening (23B) and formed integrally with an upper surface of the plate (23) so as to be coupled to the housing (15), and the tool insertion opening (24B) is formed at around a base portion of the holder portion (24) in the vicinity of a boundary between the plate (23) and the holder portion (24).
The power tool (1) according to claim 3, wherein a flange portion (26A) that extends in radial directions is formed at a lower end portion of a rubber member (26), and the rubber member (26) is fitted on an outer circumferential surface of the base portion so as to block the tool insertion opening (24B), while the flange portion (26A) is in close contact with the upper surface of the plate (23).