US20110086583A1

US20110086583A1 - Power tool, particularly a hand-held power tool

Info

Publication number: US20110086583A1
Application number: US12/997,477
Authority: US
Inventors: Joerg Maute; Florian Esenwein
Original assignee: Individual
Current assignee: Robert Bosch GmbH
Priority date: 2008-06-16
Filing date: 2009-04-22
Publication date: 2011-04-14
Also published as: EP2291264A1; EP2291264B1; WO2009153084A1; RU2011101499A; CN102066051A; DE102008002451A1

Abstract

The invention relates to a power tool, comprising a protective guard, and a clamping band to be positioned about a clamping collar for attaching a protective guard to the clamping collar of the power tool. The clamping band is tensioned by a fastening device associated with the protective guard by way of a screw. A section of the clamping band is designed as a pivoting section, which is held at an adjoining section of the clamping band in an articulating manner.

Description

The invention relates to a power tool, in particular a hand-held power tool such as an angle grinder according to claim 1 and; for a power tool; a protective guard according to claim 5.

PRIOR ART

DE 102 59 520 A1 has disclosed an electric hand-held power tool with a disk-shaped, rotating tool that is covered by a protective guard that is fastened to a clamping collar of the power tool by means of a clamping mechanism. The clamping mechanism has radially protruding end sections that are held together by a screw; as the screw is screwed in farther, the clamping mechanism is clamped tighter and exerts a radial clamping force on the clamping collar of the power tool.
The clamping mechanism is provided with a locking element that is supported in articulated fashion on the outside of the clamping mechanism band and has a locking element that protrudes through an opening in the clamping mechanism band and engages in locking fashion in a denticulation on the outer circumference of the clamping collar. The locking element must be manually pivoted between the locked position and the unlocked position. The form-locking engagement produced by means of the locking element prevents the protective guard from rotating on the clamping collar, thus improving safety, particularly in the event of a tool fracture.

DISCLOSURE OF THE INVENTION

The object of the invention is to embody a power tool, in particular a hand-held power tool, with regard to the fastening of its protective guard in such a way that even with short actuation paths for the user, a simple and secure design can be implemented and also to create a protective guard that is suitable as an attachment for such a power tool, but is also suitable as a conversion part or aftermarket part for power tools.
This object is attained with regard to the power tool by means of the defining characteristics of claim 1 and with regard to the protective guard by means of the defining characteristics of claim 5.
In the power tool according to the invention, the pivoting open of the pivoting section during the releasing of the clamping band not only releases the clamping force, which is exerted by the clamping band and acts radially on the clamping collar, but also simultaneously produces a certain expansion of the diameter of the clamping band merely by the release of the clamping force. In addition, the diameter of the clamping band can also be expanded by exerting a slight manual force so that the clamping band as a whole, including any optional locking elements or locking means situated thereon, can be brought into the release position. In this case, it is possible to influence an actuation path of the actuating element, the magnitude of the expansion of the clamping band diameter, and the magnitude of the pivot angle of the pivoting section in a number of ways, for example, by the given length of the pivoting section in the circumference direction, the bending elasticity of the pivoting section of the clamping band in comparison to the bending elasticity of the part of the clamping band supporting the pivoting section, the material selection, and/or the respective cross-sectional dimensioning and design. It is thus possible to implement working conditions for the user that permit a quick, secure clamping and releasing matched to the respective overall design, even taking into account possibly required different radial actuation paths in the region of the pivoting section as well as the part of the clamping band that supports the pivoting section, despite the possibility of executing a clamping action and possibly also a locking engagement by means of only one actuating element.
According to a preferred embodiment, preferably the pivoting section—but possibly also the part of the clamping band supporting it—must be correspondingly provided with additional locking means or such locking means must be actuated by means of the pivoting section and/or the part of the clamping band supporting it; these locking means can be quickly and securely moved into the locked position or the unlocked position.
The power tool onto whose clamping collar the protective guard is to be fastened by means of the clamping band, is suitably provided with a denticulation extending in the circumference direction on the outer circumference of the clamping collar. This denticulation is used for the engagement of the locking means provided on the clamping band, in particular on the pivoting section of the clamping band, when the clamping band is clamped in position. A groove extending in the circumference direction is optionally provided on the clamping collar, which is preferably used for the axial securing in that a pin, a lug, or the like embodied on the clamping band or protective guard engages in this circumferential groove. Possible embodiments include a separate embodiment of the circumferential groove and the denticulation extending in the circumference direction as well as a coupled embodiment in which the denticulation, with the individual tooth-shaped recesses situated one after another in the circumference direction, extends in the axial direction starting directly from the circumferential groove.
The protective guard according to the invention is used for a power tool, in particular a hand-held power tool such as an angle grinder; the protective guard covers a rotary-supported tool of the power tool and is fastened to a clamping collar of the power tool with the aid of a fastening device. The fastening device has a clamping band that is placed around the clamping collar and clamped to it by means of an actuating element. A section of the clamping band to be placed around the clamping collar is embodied in the form of a pivoting section that is supported on the clamping band in pivoting fashion in relation to an adjoining section. As the actuating element is loosened, the pivoting section of the clamping band is moved into a position in which it is pivoted open in the radial direction.
In a preferred embodiment, the inside of the clamping band, particularly in the region of the pivoting section, is provided with at least one locking element, which, when the clamping band is in the clamped position; rests against the clamping collar and preferably engages in a form-locked fashion in an associated locking recess on the outside of the clamping collar. When the pivoting section is pivoted open, the locking element extending radially inward is automatically moved into the unlocked position. To fasten the protective guard, the pivoting section is pivoted in the opposite direction, from a pivoted-open position into a position situated close to the clamping collar, which simultaneously causes the locking elements on the inside of the pivoting section to move into the locked position.
The pivotability of the pivoting section is suitably of sufficient magnitude for the locking elements on the inside to remain in the unlocked position in the pivoted-open state. In the clamped state, though, which simultaneously constitutes the locked position, the pivoting section suitably assumes the same curvature as the adjoining clamping band sections so that the clamping band including the pivoting section is circular.
If need be, a locking element is provided on a section of the clamping band outside the pivoting section. This locking element or these locking elements can be provided in addition to or alternatively to the locking element on the pivoting section.
According to a preferred embodiment, the actuating element exerts a force that moves the pivoting section into the pivoted-open position. For example, if the actuating element is embodied in the form of a screw, the head or the free end surface of the screw can rest against a component of the pivoting section and can move the pivoting section either actively into the pivoted-open position or can permit a pivoting-open by means of spring force; in the latter case, the actuating element does not move the pivoting section actively into the pivoted-open state, but instead holds the pivoting section in opposition to the force of the spring element in the clamped position. When the actuating element is shifted into the relaxed position, the actuating element shifts the pivoting section either actively or passively into the pivoted-open position.
The component on the pivoting section that is acted on by the actuating element is preferably embodied, for example, in the form of a hold-down device; as it is loosened, the actuating element acts on the hold-down device the pivoting section so that the pivoting section is shifted into a radially pivoted-open position. The hold-down device can extend radially outward on the clamping band, but an embodiment with an additional tangential component is also possible. As the actuating element—for example embodied in the form of a screw—is loosened, the screw presses against the hold-down device, thus acting on the pivoting section in the direction toward the expanded position. If need be, the pivoting section is spring-loaded into the expanded position; in the fastened state, the screw acts on the hold-down device, thus securing the pivoting section in the pivoted-in position. As the screw is loosened, the pivoting section can pivot outward in response to the action of the spring force. The spring force is produced either by means of a separate spring element, which can be situated for example in the hinge of the pivoting section, or by means of the internal stress of the pivoting section, which can, for example, be achieved through a corresponding stamping of the hinge joining the pivoting section to the remaining sections of the clamping band. In this case, the hinge is preferably embodied in a fashion similar to a film hinge, in the form of a section with a reduced wall thickness in the clamping band or by means of a stamped indentation that permits the pivoting section to pivot open.
A protective guard, which as a functional unit with its fastening device also constitutes a replacement part and/or aftermarket part, can also be used in many power tools—at least without significant adaptation expense—as a replacement for protective guards of a different design.
The invention also relates to the clamping band as such, that is in particular provided for fixing the protective guard on the clamping collar of the power tool and that enables execution of this fixing action in a quick, easy, secure, optionally also lockable way, with a low degree of complexity and with an actuation that is easy for the user, in that it has a circumference section that can be pivoted out and that functions as a pivoting section, which is acted on by the actuating element and can be pivoted into a radially pivoted-out release position, it being possible to achieve this pivoting either actively by means of the actuating element or also passively by means of a spring arrangement or the like after the release by means of the actuating element.
Other advantages and suitable embodiments can be inferred from the remaining claims, the description of the drawings, and the drawings themselves.

FIG. 1 is a view of a detail of a power tool whose clamping collar has a protective guard clamped onto it by means of the latter's fastening device; the fastening band comprises a clamping band that has a pivoting section, which, in the released state of the clamping band, can be pivoted by means of a hinge into an expanded position,

FIG. 2 is a depiction that corresponds to the one in FIG. 2, but in the released state of the fastening device, in which the pivoting section is situated in the pivoted-open, radially expanded position,

FIG. 3 shows a protective guard with a fastening device in a modified embodiment,

FIG. 4 shows the protective guard and fastening device in another modified embodiment,

FIG. 5 shows a bearing flange of the power tool, with a clamping collar in which a bearing for a tool of the power tool is accommodated; the outer circumferential surface of the clamping collar supporting the protective guard is provided with a circumferential groove with a denticulation with which a locking element on the inside of the clamping band is to be brought into a locked position,

FIG. 6 shows a bearing flange similar to the one in FIG. 5, but with a separate, axially offset embodiment of the circumferential groove and a denticulation extending around the circumference.

In the figures, parts that are the same have been provided with the same reference numerals.
FIG. 1 shows a protective guard 1 that is fastened to a power tool, in particular a hand-held power tool such as an angle grinder. The fastening function is provided by a fastening device 5 that encompasses a cylindrical collar 4, which is embodied of one piece with the main body of the protective guard 1 and is slid onto a clamping collar of the power tool. A bearing 3 for rotary support of the tool is contained in the clamping collar 2.
The fastening device 5 for fastening the protective guard 1 to the clamping collar 2 includes a clamping band 6, which is embodied in the form of a clamping mechanism and is for clamping by means of a screw 10. The screw 10 constitutes an actuating element for clamping and releasing the clamping band 6 and is guided through the radially protruding end sections 6 a and 6 b at the ends of the clamping band, each of which is provided with a respective opening through which the screw is inserted. The screw is secured to the clamping band by means of a nut. The longitudinal axis of the screw 10 extends in a tangential direction in relation to the clamping band 6 in the closed state.
The clamping band 6 has a pivoting section 7 that is a component of the clamping band, extends over an angular segment of the clamping band, and is placed around the clamping collar 2 of the power tool. The pivoting section 7 is connected to an immediately adjacent section 8 of the clamping band by means of a pivot or swivel joint 9; the hinge 9 has a rotation axis that extends parallel to the rotation axis of the tool. The hinge 9 makes it possible for the pivoting section 7 to be pivoted around the hinge out into a radially expanded position.
In FIG. 1, the clamping band 6 is depicted in the clamped position in which the screw 10 is tightened until the clamping band 6 is pulled tight around the clamping collar 2 and exerts a radial clamping force on the clamping collar, thus connecting the protective guard to the clamping collar.
The inward-facing side of the pivoting section 7 is provided with two locking elements 11 that are oriented radially inward and in the clamped state of the clamping band 6, lie in a locked position with associated recesses in the circumference surface of the clamping collar 2. In the clamped state of the clamping band, the locking elements 11 produce a locking action that acts in the circumference direction and suitably also in the axial direction. This locking action prevents the protective guard 1 from being able to rotate on the clamping collar 2 and, provided that the locking action also acts in the axial direction, prevents the protective guard 1 from being able to detach from the clamping collar in the axial direction.
Another locking element 14 is situated on the inside of the clamping band 6 outside of the pivoting section 7. This additional locking element 14 is in particular used to produce the axial securing on the clamping collar.
On the outside, adjacent to the screw 10, the pivoting section 7 is provided with a radially protruding hold-down device 12 against which the head of the screw 10 rests. The function of the hold-down device 12 is to facilitate the pivoting-open motion of the pivoting section as the screw 10 is loosened.
FIG. 2 shows the fastening device 5 in the released state in which the pivoting section 7 is pivoted radially open around its hinge 9 so that the pivoting section 7 is spaced radially apart from the inner diameter 13 that is enclosed by the clamping band 6 in the clamped state. When the screw 10—which functions as an actuating element of the fastening device 5—is loosened, the head of the screw presses against the hold-down device 12. Since the hold-down device 12 is situated on the pivoting section 7 spaced apart from the axis of the hinge 9, the contact between the screw and hold-down device accompanied by the unscrewing of the screw from the end sections 6 a and 6 b at the ends of the clamping band 6 causes the pivoting section 7 to pivot open around its hinge 9. Conversely, with a tightening, i.e. a screwing-in of the screw 10, the distance between the end sections 6 a and 6 b is reduced, thus acting on the pivoting section 7 in the direction toward its clamped position in which the inside of the pivoting section 7 coincides with the inner diameter 13 and the locking elements 11 on the inside of the clamping section engage in locking fashion in associated recesses in the clamping collar.
The hinge 9 between the pivoting section 7 and the adjoining section 8 of the clamping band 6 can be manufactured in a simple mechanical fashion by virtue of the fact that the end region of the pivoting section 7 is bent into the shape of a hook and encompasses an axle pin that is provided or situated at the associated terminal end of the section 8.
In addition, it can be suitable to load the pivoting section 7 with the force of a spring element, either in the direction of its clamped position or in the direction of its pivoted-open position. The spring element can be embodied of one piece with the clamping band 6, for example by virtue of the fact that the hinge 9 is simply embodied in the form of a thinner wall segment or is embodied as a stamped indentation in the clamping band, and a prestressing force is exerted on the pivoting section 7. It is also possible, however, for the spring element to be embodied as a separate component, which is situated, for example, in the region of the hinge 9 and exerts force on the pivoting section in the direction toward one of its end positions.
In the exemplary embodiment according to FIG. 3, the clamping band 6 is likewise equipped with a pivoting section 7 that can pivoted radially open and that is rotatably connected to the adjoining section 8 of the clamping band by means of the hinge 9. However, the end sections 6 a and 6 b are embodied not as radial projections, but as circumferentially extending, overlapping sections that are held together by the screw 10, with the screw 10 extending in the radial direction.
The hold-down device 12 rests against the head of the screw 10 and extends on the outside of the pivoting section 7 with a radial component and a component extending in the circumferential direction. The freely extending end of the hold-down device 12 rests against the head of the screw 10 so that when the screw 10 is loosened, the hold-down device is bent back, thus producing a force that, together with the distance from the hinge 9, results in a pivoting-open moment.
The exemplary embodiment according to FIG. 4 shows a combination of the exemplary embodiments from FIGS. 1 and 3. In FIG. 4, the end sections of the clamping band 6 are embodied as radially projecting; in this region, the screw 10, functioning as a fastening element, is inserted through openings in the end sections and holds them together with a clamping force. The hold-down device 12, whose freely extending end rests against the head of the screw 10, is embodied in a way that corresponds to the one in the third exemplary embodiment and extends on the outside of the pivot section 7 with a component oriented in the radial direction and a component oriented in the circumference direction.
FIG. 5 shows a bearing flange 19 of the power tool, including a base plate 20 and the clamping collar 2 that is embodied of one piece with the base plate and that accommodates the bearing 3 for the drive spindle 4. A denticulation 21 is provided in the outer circumference surface of the clamping collar 2 and is composed of a multitude of axially extending tooth-shaped recesses distributed over the circumference, which are associated with the locking element of the locking component; in the locked position, the locking element protrudes into a respective tooth-shaped recess. This produces a form-locked engagement in both the circumference direction and axial direction.
The tooth-shaped recesses each extend axially starting from a circumferential groove 22 that extends around the entire circumference of the clamping collar 2. The locking element of the locking component can be slid along the circumferential groove 22. If need be, however, a component embodied separately from the locking element, e.g. a pin or the like, protrudes into the circumferential groove and thus secures the clamping mechanism and protective guard to the clamping collar in the axial direction.
In the exemplary embodiment according to FIG. 6, which likewise shows a bearing flange 19 equipped with a base plate 20 and clamping collar 2, the denticulation 21 is embodied separately from the circumferential groove 22. The denticulation 21 is situated adjacent to the top surface of the base plate 20, whereas the circumferential groove 22 is situated adjacent to the end surface of the clamping collar 2. In this embodiment, it is mandatory for a component embodied separately from the locking component to protrude into the circumferential groove 22, for example a pin or the like.

Claims

1-17. (canceled)

18. A power tool, in particular a hand-held power tool such as an angle grinder, having a protective guard which fastens to a clamping collar of the power tool by means of a clamping band which is placed around the clamping collar and clamped thereto by means of an actuating element and which has a pivoting section that is acted on by the actuating element and that is able to pivot into a radially pivoted-out position.

19. The power tool as recited in claim 18, wherein the clamping collar of the power tool has a denticulation extending in a circumference direction which denticulation is engaged by a locking element of the pivoting section in a locked position.

20. The power tool as recited in claim 19, wherein a circumferential groove is provided on the clamping collar.

21. The power tool as recited in claim 20, wherein tooth-shaped recesses, which extend in an axial direction on the clamping collar starting from the circumferential groove, are provided in a circumference surface of the clamping collar.

22. A protective guard for a power tool, in particular for a hand-held power tool such as an angle grinder, which fastens to a clamping collar of the power tool by means of a fastening device which has a clamping band which is placed around the clamping collar and clamped to it by means of an actuating element, wherein a section of the clamping band is embodied in the form of a pivoting section that is pivotably secured to an adjoining section of the clamping band and with a loosening of the actuating element, it is possible to move the pivoting section of the clamping band into a radially pivoted-open position.

23. The protective guard as recited in claim 22, wherein an inside of the pivoting section on the clamping band is provided with at least one locking element that rests against the clamping collar when the clamping band is clamped.

24. The protective guard as recited in claim 22, wherein as the loosening occurs, the actuating element acts on the pivoting section, which is able to move into the radially pivoted-out position.

25. The protective guard as recited in claim 23, wherein as the loosening occurs, the actuating element acts on the pivoting section, which is able to move into the radially pivoted-out position.

26. The protective guard as recited in claim 24, wherein a hold-down device is situated on the clamping band and is acted on by the actuating element.

27. The protective guard as recited in claim 25, wherein a hold-down device is situated on the clamping band and is acted on by the actuating element.

28. The protective guard as recited in claim 26, wherein as the loosening occurs, the actuating element acts on the hold-down device with a component that causes the pivoting section to expand radially.

29. The protective guard as recited in claim 27, wherein as the loosening occurs, the actuating element acts on the hold-down device with a component that causes the pivoting section to expand radially.

30. The protective guard as recited in claim 26, wherein the hold-down device extends radially outward on the clamping band.

31. The protective guard as recited in claim 30, wherein the hold-down device extends with a tangential component on the clamping band.

32. The protective guard as recited in claim 22, wherein the actuating element is embodied as a screw that acts on the pivoting section.

33. The protective guard as recited in claim 32, wherein the screw is guided through radially flaring end sections of the clamping band and the screw extends at least essentially tangential to the clamping band.

34. The protective guard as recited in claim 32, wherein the screw extends radially to the clamping band and in the clamped position, connects overlapping end sections of the clamping band.

35. The protective guard as recited in claim 22, wherein the pivoting section is connected in articulating fashion to the adjoining section of the clamping band by means of a pivoting hinge.

36. The protective guard as recited in claim 35, wherein the pivoting hinge is embodied as a separate component that is secured to the clamping band.

37. The protective guard as recited in claim 35, wherein the pivoting hinge is embodied as a section with a reduced wall thickness.