Replacement of rotatable cutting discs of a power tool

A power tool includes a rotatable support arrangement for supporting at least one cutting disc. An upper shroud member and a lower shroud member cooperate to define a volume in which the at least one cutting disc can be supported. The rotatable support arrangement can be coupled to the upper shroud member such that movement of the upper shroud member towards the lower shroud member causes the cutting disc to protrude through an opening in the lower shroud member. A biasing member urges the upper shroud member and the lower shroud member away from each other. A limiting mechanism limits the range of movement of the upper shroud member relative to the lower shroud member under action of the biasing member. The limiting mechanism can be disengaged by opening the upper shroud member via at least one hinge coupling.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to European Patent Application No. 18208929.2 filed on Nov. 28, 2018, which is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

This specification concerns facilitating a user to replace rotatable cutting discs of a power tool, for example a wall chaser.

Description of the Related Art

European patent number EP2552660B1 describes a wall chaser, which is a power tool for forming channels in a concrete surface. Objects such as cables and wires can be fed through such channels during a construction project. Wall chasers are known to carry a pair of axially offset cutting discs which in use form two parallel slots in a concrete surface. Subsequently a construction worker is required to chisel away the concrete remaining between such slots, thereby leaving a channel of the kind heretofore mentioned. It will be appreciated that the cutting discs are subject to wear and need replacing from time-to-time. Wall chaser products are known in which users must partially disassemble their wall chaser product, in other words physically separate respective parts thereof, to enable user access to the cutting discs for replacement or for other reasons e.g. to change the distance between cutting discs and thus cutting width. Furthermore, some wall chaser products require surprisingly high levels of dexterity to access the cutting discs thereof and can be difficult to open up in order to provide user access to the cutting discs for replacement or otherwise. Aspects of the present invention are conceived to address the foregoing.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided a power tool comprising: a rotatable support arrangement for supporting at least one cutting disc and being configured to be rotatably driven by an electric motor; an upper shroud member and a lower shroud member which cooperate to define a volume in which the at least one cutting disc can be supported, the rotatable support arrangement coupled to the upper shroud member such that movement of the upper shroud member towards the lower shroud member causes the at least one cutting disc to protrude through an opening in the lower shroud member; biasing member for urging the upper shroud member and the lower shroud member away from each other; a limiting mechanism for limiting the range of movement of the upper shroud member relative to the lower shroud member under action of the biasing member, a first part thereof being carried by the upper shroud member and a second part thereof being carried by the lower shroud member; wherein the limiting mechanism can be disengaged by opening the upper shroud member via at least one hinge coupling, thereby increasing the range of relative movement of the upper and lower shroud members.

The upper shroud member may comprise a first shroud part and a second shroud part that are configured to move relative to each other via at least one the hinge coupling.

The first shroud part and the second shroud part may be configured to move relative to each other via a single hinge coupling.

The upper and lower shroud members may be configured to pivot relative to each other about a first axis and the or each the hinge coupling may permit relative movement between the first and second shroud parts about a respective axis orthogonal to the first axis.

The first shroud part and the second shroud part may be maintained in a closed configuration by a securing mechanism that can be selectively released by a user.

The limiting mechanism may be configured such that when the first and second parts thereof are urged against each other upon a user moving the upper and lower shroud members towards each other one of the first and second parts of the limiting mechanism causes the other to recoverably flex so that they can move past each other, however, upon the first and second parts of the limiting mechanism being subsequently brought back into contact with each other under action of the biasing member urging the upper and lower shroud members away from each other the first and second parts of the limiting mechanism restrict the extent to which the upper and lower shroud members can be moved away from each other under action of the biasing member.

The first and second parts of the limiting mechanism may comprise a spring that defines a first surface along which the other of the first and second parts of the limiting mechanism can ride for facilitating such parts to move past each other when urged against each other upon a user moving the upper and lower shroud members towards each other, the spring also defining a second surface against which the other of the first and second parts of the limiting mechanism can rest when such parts are subsequently brought back into contact with each other under action of the biasing member urging the upper and lower shroud members away from each other.

A blocking member of the shroud part carrying the spring may block deflection of the spring when the other of the first and second parts of the limiting mechanism urges against the second surface of the spring under action of the biasing member urging the upper and lower shroud members away from each other, thereby limiting the extent to which the upper and lower shroud members can move away from each other.

The blocking member may be an integral internal surface of the shroud part which carries the spring or is a feature coupled to that shroud part.

The spring may be metallic.

The other of the first and second parts of the limiting mechanism for cooperating with the spring may comprise a rigid body having a first surface for engaging the first surface of the spring and a second surface for engaging the second surface of the spring, optionally the second surface of the rigid body having a larger surface area than the first surface thereof.

The rigid body may further comprise a ramped portion between the first surface thereof and the second surface thereof.

The other of the first and second parts of the limiting mechanism for cooperating with the spring may comprise a rigid body having a rod like shape.

The rigid body may be an integral part of the shroud member that is free from carrying the spring.

The heretofore described tool may be a rotary cutting tool for cutting masonry, optionally wherein the tool is a wall chaser.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2illustrate a power tool, which in the embodiment described hereafter is a wall chaser10.FIG. 1illustrates the wall chaser10in a ready-to-use configuration andFIG. 2illustrates the wall chaser10in a cutting-disc-changing configuration.

The wall chaser10has a rotatable support arrangement12for supporting a pair of cutting discs14. The cutting discs14can be mounted to a shaft16of the support arrangement12in a manner familiar to persons skilled in the art. For example, the cutting discs14can be placed around the shaft16with a spacer element between them, wherein a nut18is then threaded onto the shaft16. The action of threading the nut18onto the shaft16causes the first cutting disc to be mounted on the shaft16to be essentially sandwiched between a supporting flange of the wall chaser10and a first side of the spacer element, whereas the second cutting disc to be mounted on the shaft16will be essentially sandwiched between a second side of the spacer element and the nut18. The cutting discs14are thus rotationally locked relative to the shaft16such that upon an electric motor100of the wall chaser10causing the shaft16to rotate the cutting discs14will be rotationally driven as well. It will be appreciated that various configurations and combinations of spacer elements can be used depending on the required distance between the cutting discs14. For example, in another usage implementation the spacer element used could be shorter in length thereby providing a smaller distance between the cutting discs14. Alternatively, the spacer element used could be longer in length (or more than one spacer element could be used) thereby providing a greater distance between the cutting discs14.

An upper shroud member20and a lower shroud member22cooperate to define a volume in which the cutting discs14can be supported. The shaft16extends from an internal surface of the upper shroud member20such that movement of the upper shroud member20towards the lower shroud member22causes the cutting discs14to protrude through an opening24in the lower shroud member22; this opening24extending through the base of the wall chaser10which is engaged with a work surface in use as shown inFIG. 1. In this manner the cutting discs14can be brought into engagement with a work surface e.g. a masonry surface in use.

The upper shroud member20is pivotally coupled to the lower shroud member22. Biasing member urges the upper shroud member20and the lower shroud member22away from each other. In this embodiment, the biasing member is a torsion spring26, as shown inFIG. 3. With reference toFIG. 4the lower shroud member22has a pair of flanges28,30each having an opening extending therethrough. A bolt member32extends through these openings, wherein the torsion spring26wraps around the bolt member32in the space between the flanges28,30. A first arm26aof the torsion spring26is for urging against the lower shroud member22and a second arm26bof the torsion spring26is for urging against the upper shroud member20. The upper shroud member20is pivotally coupled to the lower shroud member22so when a user pivots such members towards each other the torsion spring26is compressed, wherein upon releasing such members the torsion spring26urges them apart. Looking atFIG. 2the feature of the upper shroud member20which the second arm26bof the torsion spring26urges against is the connecting element19.

Referring back toFIG. 1, one hand of a user grips the primary handle11in use, whereas the other hand grasps secondary handle13. Pushing downwards on the secondary handle13in use causes the upper shroud member20to pivot towards the lower shroud member22and the cutting discs14to plunge into the masonry surface to be cut. Various internal features required for the wall chaser10to function as heretofore described will be apparent to persons skilled in the art, including a battery for powering an electric motor and a power train for transferring torque from the electric motor to the shaft16for rotating the cutting discs14. Moreover, a trigger15is provided on the primary handle11for enabling a user to selectively cause actuation of the electric motor and thereby rotation of the cutting discs14.

The upper shroud member20is formed of two parts, a first shroud part20aand a second shroud part20bwhich are coupled together via a hinge coupling25. The upper shroud member20can thus be reconfigured between a closed configuration as inFIG. 1and an open configuration as inFIG. 2. The first shroud part20aand the second shroud part20bare maintained in a closed configuration by a securing mechanism that can be selectively released by a user. In this embodiment the securing mechanism comprises a first latch part27aon the first shroud part20athat can be releasably coupled to a second latch part27bon the second shroud part20b, but other suitable mechanisms will be apparent to persons skilled in the art.

A limiting mechanism is provided for limiting the range of pivotal movement of the upper shroud member20relative to the lower shroud member22under action of the torsion spring26when the upper shroud part20is in the closed configuration. A first part34aof the limiting mechanism is carried by the upper shroud member20and a second part34bof the limiting mechanism is carried by the lower shroud member22.

With reference toFIGS. 5 and 6, the first part34aof the limiting mechanism is provided on an internal surface of the upper shroud member20, in the embodiment shown on the internal surface of the second shroud part20b. The view inFIG. 6includes a cross sectional view of the second shroud part20b, otherwise the outer surface thereof would obscure the features extending from its internal surface. Protrusions36extending from the internal surface of the second shroud part20bcooperate to define a substantially L-shaped channel37, wherein an opening38is left in communication with the channel37. A metallic spring feature or spring40is received in the channel37and maintained therein by interference fit with the internal surfaces of the protrusions36. The metallic spring40extends from the channel37via the opening38.

The metallic spring40has a first surface or section42that extends from the opening38of the channel37into contact with a blocking surface44. In this embodiment the blocking surface44is defined by a blocking member46coupled to the internal surface of the upper shroud member20, in the embodiment shown on the internal surface of the second shroud part20b. The metallic spring40also has a second surface or section section43that extends away from the blocking surface44. The first and second sections42,43of the metallic spring40define an acute angle A between them. The purpose of these specific features will become apparent upon reading further.

With continued reference toFIGS. 5 and 6, the second part34bof the limiting mechanism is carried by the lower shroud member22and can comprise a rigid body integrally formed with the lower shroud member22. The rigid body forming the second part34bhas a first surface48and a second surface50, wherein the second surface50has a larger surface area than the first surface48. A ramped portion52is provided between such first and second surfaces48,50.

Looking atFIG. 2, consider the scenario in which a user closes the upper shroud member20and then urges the upper shroud member20towards the lower shroud member22. This involves the user closing the first and second parts20a,20bof the upper shroud member20and securing the first latch part27ato the second latch part27b. Upon subsequently pivoting the upper shroud member20towards the lower shroud member22, against bias of the torsion spring26, the first section42of the metallic spring40carried by the upper shroud member20will be brought into engagement with the first surface48of the second part34bcarried by the lower shroud member22. Upon further pivoting the upper shroud member20more towards the lower shroud member22the second part34bcooperates with the metallic spring40to cause deflection of the metallic spring40. In other words, the metallic spring40is caused to recoverably flex by the second part34bthus enabling such features to move past each other. The upper shroud member20can thus be pivoted further towards the lower shroud member22by a user against bias of the torsion spring26.

Looking atFIG. 6, the first section42of the metallic spring40is configured to be ramped relative to the first surface48of the second part34bwhen they initially engage. This reduces the extent of deflection required by the metallic spring40to move past the second part34bcompared to if the first section42of the metallic spring40simply extended directly from the opening38along the axis of the channel37.

With continued reference toFIG. 6, upon a user subsequently refraining from urging the upper shroud member20towards the lower shroud member22against bias of the torsion spring26the torsion spring26will urge such members apart. As the upper shroud member20pivots away from the lower shroud member22under bias of the torsion spring26the second section43of the metallic spring40carried by the upper shroud member20is brought into engagement with the second surface50of the second part34bcarried by the lower shroud member22. The second surface50of the second part34bthus cooperates with the metallic spring40to cause deflection of the metallic spring40in the opposite direction to that heretofore described, however, the extent of such deflection is limited by the blocking surface44. In other words, the blocking surface44prevents the spring element40from deflecting sufficiently to enable it to move past the second part34bas the upper shroud member20is pivoted away from the lower shroud member22under bias of the torsion spring26. The extent of pivotal movement of the upper shroud member20relative to the lower shroud member22is thereby restricted. Moreover, the blocking surface acts as heretofore described to restrict the lower shroud member22from falling away from the upper shroud member20under gravity when a user lifts the tool up.

It is here mentioned that when the upper shroud member20is at its upper limit of pivotal movement away from the lower shroud member22(defined by engagement between the second section43of the metallic spring40and the second surface50of the second part34bas heretofore described) the cutting discs14carried by the wall chaser10do not protrude through the opening24in the base thereof. The cutting discs14only protrude through the opening24in the base of the wall chaser10when a user urges the upper shroud member20towards the lower shroud member22against bias of the torsion spring26in use.

To enable replacement of the cutting discs14a user must release the first and second latch parts27a,27bto open the upper shroud member20. On doing so the second shroud part20bcan be pivoted away from the first shroud part20aabout the hinge coupling25, thereby the metallic spring40carried by the upper shroud member20is moved out of engagement with second part34bcarried by the lower shroud member22. The heretofore described limiting mechanism is thus disengaged and the extent of pivotal movement between the upper shroud member20and lower shroud member22is increased. In the open configuration of the upper shroud member20, when a user holds the wall chaser10from only the secondary handle13the lower shroud part22pivots away from the upper shroud part20under the influence of gravity and bias of the torsion spring26.

With further reference toFIG. 2, when the upper shroud part20is in the open configuration, parts of the wall chaser10can pivot about two axes of freedom. The first such axis45is defined by the hinge coupling25and the second such axis47is defined by the pivotal connection between the upper and lower shroud members, wherein such axes are orthogonal relative to each other. Users of the wall chaser10are thus provided with quick and easy access to the cutting discs14mounted to the shaft16for facilitating their replacement or otherwise e.g. changing the distance between the cutting discs14by modifying the arrangement of spacer elements heretofore described which will be familiar to persons skilled in the art. Also, since features of the wall chaser10merely hinge apart to enable blade replacement the risk of a user losing a feature or not reassembling it correctly is reduced.

Lastly, it is pointed out that after a cutting disc replacement operation the wall chaser10can be reconfigured into its ready-to-use configuration illustrated inFIG. 1in multiple ways. For example, starting from the configuration illustrated inFIG. 2a user may secure the first and second shroud parts20a,20bof the upper shroud member20and then urge the upper shroud member20towards the lower shroud member22to engage the limiting mechanism as heretofore described.

Alternatively, starting from the configuration illustrated inFIG. 2a user may urge the first shroud member20towards the lower shroud member22against the torsion spring26by pushing down on the secondary handle13. Subsequently the user may then secure the first and second shroud parts20a,20bof the upper shroud member20together before releasing the pressure exerted against the torsion spring26. On releasing such pressure, the upper shroud member20will be pivoted away from the lower shroud member22by the torsion spring26, thereby engaging the second section43of the metallic spring40with the second surface50of the rigid member34bfor restricting further pivotal movement of the shroud members away from each other under bias of the torsion spring (and gravity when the tool is lifted).

In some embodiments, the blocking surface44is not defined by a blocking member46coupled to the internal surface of the upper shroud member20, whereas instead it is merely an internal surface of the shroud part which carries the metallic spring40e.g. the inner surface of the shroud part or a flange integrally formed with the shroud part. In some embodiments the blocking surface44is a rib integrally formed with the upper shroud member20and extending from an inner surface thereof.

Although the first and second heretofore mentioned axes45,47defining the degrees of freedom of movement of respective features of the wall chaser10have been described as being orthogonal relative to each other, in some embodiments this need not necessarily be the case provided the wall chaser10can be opened and closed in substantially the same manner for cutting disc replacement i.e. opening the upper shroud member20disengages the limiting mechanism.

Looking atFIG. 2, the connecting element19couples directly to the first shroud part20aof the upper shroud member20, thus providing that only the second shroud part20bmoves about the hinge connection25. In some embodiments the connecting element19may be shaped such that both the first shroud part20aand the second shroud part20bare separately coupled thereto about respective hinge couplings. In other words, the first shroud part20amay be coupled to the connecting element19via a first hinge coupling and the second shroud part20bmay be coupled to the connecting element19via a second hinge coupling; thereby providing that in such embodiments both the first and second shroud parts20a,20bcan be hingedly moved relative to each other in order to open the upper shroud member20.

Although the protrusions36, metallic spring40and blocking surface44have been described as carried by the upper shroud member20; and the second part34bhas been described as carried by the lower shroud member22; it will be appreciated that such an arrangement could be reversed. For example, the protrusions36, the metallic spring40and the blocking surface44could alternatively be carried by the lower shroud member22; and the second part34bcould alternatively be carried by the upper shroud member20provided that the second part34bis capable of being disengaged from the metallic spring40when the shroud parts of the upper shroud member20are opened relative to each other.

In some embodiments, the spring feature40need not necessarily be metallic and could be plastic or rubber for example, provided it is able to perform the same function as the metallic spring40heretofore described.

Although the foregoing embodiments are described as including a torsion spring26for urging the upper shroud member20away from the lower shroud member22in some embodiments an alternative biasing member could be used such as a cap spring, coil spring, clock spring or pressure spring.

It will be appreciated that in other embodiments, respective features need not necessarily have the same shape and configuration of the parts heretofore described provided they achieve the same function. For example, with reference toFIGS. 7 and 8(wherein like features are denoted with similar reference numerals to those used up to now but increased by 100) in one embodiment the second part134bof the limiting mechanism carried by the lower shroud member122may be a rod or pin extending from the lower shroud122. As for the first part134aof the limiting mechanism carried by the upper shroud member the metallic spring feature or spring140cooperates with a blocking surface144formed by a rib extending from an internal surface of the second shroud part120b. Upon closing the first and second shroud parts120a,120band pushing the upper shroud member120towards the lower shroud member122against spring bias as heretofore described, the rod or pin will cooperate with the metallic spring portion140causing it to deflect and move past the rod or pin and spring back to its original configuration. Upon a user refraining from pushing the upper shroud member120towards the lower shroud member122the spring bias will cause the section143of the metallic spring140to engage the rod or pin which will urge it into contact with the blocking surface144, thereby restricting the spring bias from being able to urge the upper and lower shroud members120,122apart. Moreover, the blocking surface144acts as to restrict the lower shroud member122from falling away from the upper shroud member120under gravity when a user lifts the tool up. The mechanism can be released by opening the upper shroud member120via the hinge coupling125.

Although the foregoing is described in the specific context of a wall chaser10it will be appreciated that the teachings herein could be applied in the context of other power tools having rotatable cutting discs that are shielded from user access in use but that a user must have access to in order to replace them, e.g. circular saw power tools. It will thus further be appreciated that in some embodiments the power tool in which the foregoing teachings are applied could have only a single cutting disc.

Finally, it will be appreciated that whilst various aspects and embodiments have heretofore been described, the scope of the present invention is not limited thereto and instead extends to encompass all arrangements, and modifications and alterations thereto, which fall within the spirit and scope of the appended claims.