US20060068690A1

US20060068690A1 - Cover device for a power tool

Info

Publication number: US20060068690A1
Application number: US11/238,494
Authority: US
Inventors: Christian Koschel; Alexander Funk
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2004-09-29
Filing date: 2005-09-28
Publication date: 2006-03-30
Also published as: DE102004047278A1; EP1642680A1; DE502005006457D1; EP1642680B1

Abstract

A cover device for partially covering a front, in an axial direction, side of a disc-shaped working tool (10) of a power tool includes a bearing element (22) securable on the shielding member (12), which partially radially covers the working tool (10), and having a bearing surface (28) abutting, at least regionwise, an outer surface (14) of the shielding member (12), a protective disc (30) extending substantially transverse to the bearing surface (28) of the bearing means (22), and engaging-from-behind elements (24) provided at opposite tangential ends of the bearing surface (28), respectively, with at least one of the engaging-from-behind elements (24) being elastically pivotal in a radial direction.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a cover device for partially covering a front, in an axial direction, side of a disc-shaped grinding or separating tool of a power tool, in particular, of an angle grinder. The cover device is designed in particular to be retrofitted on the power tool. The cover device is provided with a bearing member having a bearing surface securable, when required, over a shielding member that partially covers the working tool. The bearing surface at least regionwise abuts the outer surface of the strip-shaped shielding member. The cover device also includes a protective disc which extends substantially transverse to the bearing surface and which partially covers the front, in the axial direction, side of the working tool.
2. Description of the Prior Art
Most of angle grinders are equipped, standardwise, with a shielding member which is formed as a protective plate having an acruate cross-section in the longitudinal direction and which is secured to a truncated cone section provided on the power tool head of the power tool. The shielding member partially covers the working tool in the radial direction. With the power tool having such shielding member, the power tool can be retrofitted, if needed, in such a way that the working tool front side would be partially covered in the axial direction. With the tool being partially covered in the axial direction, the user becomes effectively protected from accelerating material particles, in particular sparks, also in the axial direction. On the other hand, with the protective disc extending substantially transverse to the bearing section, the cover means forms a space around the working tool a major part of which is closed. The closed space insures an effective suction of removable material particles.
The language “substantially transverse,” which is used above, means that the protective disc is arranged somewhat transverse to the overall direction of the bearing surface independent from the shape of the bearing surface of the bearing means.
German document 94 03 777 discloses a cover device for an angle grinder and which has a protective disc on which an additional cover is pivotally supported. The disc has a jacket element that partially extends over its circumference and that surrounds the shielding member. The cover device is forcelockingly secured on the angle grinder.
The known cover device covers the working tool well during operation. However, the manufacturing costs of the device of DE 94 03 777 are relatively high. In addition, the means that provides for the forcelocking connection of the cover device on the power tool, such as, e.g., clamp screws, are either tedious to operate or are not capable to absorb forces acting on the cover device during the power tool operation, such as, e.g., tangentially acting impacts, without the cover device being displaced.
An object of the present invention is to provide a cover device in which the drawbacks of the known tool are eliminated.
Another object of the present invention is to provide a cover device that can be produced with reduced manufacturing costs.
A further object of the present invention is to provide a cover device that can be rapidly mounted on or dismounted from the power tool.
Yet a further object of the present invention is to provide a cover device that would be reliably held on the power tool during operation.

SUMMARY OF THE INVENTION

These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing engaging-from-behind elements at opposite tangential ends of the bearing surface, respectively, with at least one of the engaging-from-behind elements being elastically pivotal, i.e., being pivotal with a recoverable deformation in a radial direction for changing a distance a between the engaging-from-behind elements.
The engaging-from-behind elements provide for a particularly easy locking of the cover device with matching locking means, with the distance between the engaging-from-behind elements being increased by application of corresponding external forces. When the cover device is mounted on the power tool, it can easily be pinned on the shielding member, with the distance between the engaging-from-behind elements assuming its initial value upon removal of external forces as a result of action of restoring forces which return the at least one engaging-from-behind element to its initial position. Upon the distance between the engaging-from-behind element returning to its initial value, they become locked with the matching locking means of the power tool. Upon release of the cover device, the engaging-from-behind elements are displaced away from each other against the restoring force in order to break the locking between the engaging-from-behind elements and the matching locking means.
According to a particular advantageous embodiment of the present invention, the engaging-from-behind elements extend radially inward from tangential limiting edges of the bearing surface of the bearing means. Thereby, formation of specific matching means, e.g., in form of grooves or bores, on the shielding member can be avoided, which minimizes manufacturing costs. In addition, the cover device can be easily and rapidly pinned on the power tool, with the engaging-from-behind elements engaging from behind the limiting edges of the shielding member, securing the cover device in both tangentional directions.
Advantageously, the at least on of the engaging-from-behind elements is formed as a hook-shaped element securely connected with the bearing means. In addition, the protective disc is provided with a substantially radially extending slot. The slot gives the cover device a certain elasticity, providing for displacement of the engaging-from-behind elements away from each other under action of external forces, with the elements being returned to their initial position under the action of restoring forces. This makes possible an easy mounting of the cover device on the power tool and dismounting it therefrom without use of any assembly or other tools.
Alternatively, the at least one engaging-from-behind element can be formed on a spring-biased locking element. With the locking element, the cover device can be particularly reliably secured on the power tool.
Advantageously, the locking element has a spring arm, with a locking nose being formed on a free end of the arm and extending radially inwardly. The spring arm insures that the locking element automatically engages from behind a respective limiting edge upon mounting of the cover device on the power tool. Thereby, a particularly easy connection of the cover device with the power tool is insured.
Advantageously, the spring arm is formed by two, extending parallel to each other, cut-ins provided at a tangential end of the bearing surface. This insures a particularly cost-effective manufacturing of the locking element.
Advantageously, the engaging-from-behind elements are formed integrally with the remaining part of the cover device as a one-piece part, i.e., by deformation or partial removal of the material that forms the cover device. Thereby, manufacturing costs are reduced, and a stable locking element is produced.
Advantageously, the protective disc extends at least over a half-circle defined by the bearing means. Thereby, the working tool can be covered particularly well in order to protect the user from flying sparks and similar released and accelerated particles. Easy mounting and dismounting of the cover device also insure a rapid replacement of the working tool.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings show:
FIG. 1 a perspective exploded view of a power tool with a cover device according to the present invention;
FIG. 2 a perspective view of a cover device shown in FIG. 1;
FIG. 3 a a side view of the cover device shown in FIG. 2;
FIG. 3 b a cross-sectional view along line IIIb-IIIb in FIG. 3 a;
FIG. 3 c a detail IIIc in FIG. 3 b at an increased, in comparison with FIG. 3 b, scale;
FIG. 4 a a side view of another embodiment of a cover device;
FIG. 4 b a cross-sectional view along line IVb-IVb in FIG. 4 a; and
FIG. 3 c a detail IVc in FIG. 4 b at an increased, in comparison with FIG. 4 b, scale.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a power tool 2 which is formed as an angle grinder and has a housing 4 with a tool head 6. The tool head 6 has a tool spindle 8 rotatable about an axis A and on which a disc-shaped working tool 10 is secured. Further, there is provided on the tool head 6 a shielding member 12 in form of a protective plate that partially surrounds the working tool 10 in a radial direction. The shielding member 12 has an outer surface 14 having an arcuate cross-section in its longitudinal direction and a straight section in its transverse direction and the edges of which are rounded.
The working tool 10 is secured on the tool spindle 8 with a tool retaining member 16. For mounting or dismounting the working tool 10 on or from the tool spindle 8, the tool retaining member 16 is tightened or released, respectively, using an assembly tool 18 in form of, e.g., a wrench or, as shown in FIG. 1, in form of a special tool.
FIG. 1 further shows a cover device 20 according to the present invention in a position in which it is taken off the power tool 2. The cover device 20 can be mounted on the shielding member 12 or dismounted therefrom without using any assembly tools. To this end, the cover device 20 is provided with a strip-shaped bearing means 22 the shape of which substantially corresponds to the profile of the outer surface 14 of the shielding member 12.
The cover device 20 further includes inwardly projecting, engaging-from-behind elements 24 which are provided, respectively, at opposite tangential ends of the bearing means 22 and which are spaced from each other by a distance a. Upon mounting of the cover device 20 on the power tool 2, the bearing means 22 abuts the outer surface 14 of the shielding member 12, and the engaging-from-behind elements 24 contact the outer surface 14 that pushes the elements 24 away from each other. With the elements 24 being pushed away from each other, the distance a therebetween increases. The outer surface 14 is limited in the tangential direction at its opposite ends by limiting edges 26 which are snapped behind by the engaging-from-behind elements 24 due to the recovery forces generated upon displacement of the elements 24 away from each other.
As it is particularly shown in FIG. 2, the cover device 20 has, in a direction perpendicular to a section of a bearing surface 28 of the bearing means 22 which has a straight cross-section, a protective disc 30. The protective disc 30 extends over a semicircle defined by the bearing means 20 and covers, in the mounted condition of the cover device 20 on the shielding member 12, in the axial direction, the frontal side of the working tool 10 toward outside, with the protective disc 30 projecting in the axial direction partially beyond the tool spindle 8.
FIGS. 3 a-3 c shows a first embodiment of the engaging-from-behind elements 24. The elements 24 have, at their respective free ends, two hook-shaped elements 32 which are formed at the tangential ends of the bearing means 22. The hook-shaped elements 32, together with the engaging-from-behind elements 24, are formed, together with the bearing means 22, as a substantially formstable single piece. In order to be able to displace the engaging-from-behind elements 24 away from each other to increase the distance a therebetween for hooking the cover device 20 on the limiting edges 26 of the shielding member 12 and for removing the cover device 20 off the shielding member 12, there is formed, in the protective disc 30, a radial slot 34. The slot 34 permits to deform, the bearing means 22 during mounting of the cover device 20 on the shielding member 12 and dismounting of the cover device 20 from the shielding member 12. The slot 34 provides for a radial pivotal movement of the engaging-from-behind elements 24, which increases the distance a therebetween. By radially pivoting the engaging-from-behind elements 24, it is possible to move them past the limiting edges 26 in order to hook the elements on the limiting edges 26 or to release the elements 24 from the limiting edges 26.
On the inner side of the hook-shaped elements 32, there is formed a trough 36, as particularly shown in FIG. 3 c, which provides for a better holding of the hook-shaped elements 32 on respective limiting edges 26 of the shielding member 12.
FIGS. 4 a-4 c show an alternative, second embodiment of the engaging-from-behind elements 24. According to this embodiment, the engaging-from-behind elements 24 are formed on a locking nose 38 of an elastically resilient locking element 40. The locking element 40 has a spring arm 42 that is formed by two tangentional, extending parallel to each other, cut-ins 44 provided at respective tangential ends of the bearing means 22. The cut-ins 44 provide for elastic pivotal movement of the engaging-from-behind elements 24 in the radial direction relative to the bearing means 22 in order to change the distance a therebetween.
With both embodiments of the engaging-from-behind elements 24, the cover device 20 can be rapidly pinned on the shielding member 12, without using any additional tools.
In both embodiments, the engaging-from-behind elements 24 engage the limiting edges 26 in order to secure the cover device 20 on the shielding member 12 in the tangential and radial direction.
Simultaneously, the cover device 20 is secured in the axial direction with the partially arched bearing surface 28 the profile of which corresponds to that of the outer surface 14 and which substantially abuts the outer surface 14.
According to a further embodiment of the cover device 20, only one engaging-from-behind element 24 is provided on the locking element, whereas the other engaging-from-behind element is connected with the bearing member 22 in a formstable manner. In this case, upon mounting of the cover device 20, the engaging-from-behind, form-stable element 24 should be hooked about a respective limiting edge 26, and the cover device 20 should be pivoted about this edge in order to have the other, elastic engaging-from-behind element 24 snap from behind the other limiting edge 26.
In the mounted condition of the cover device 20, the protective disc 30 would cover the frontal side of the working tool 10 in the axial direction in order to protect the user better from sparks which are generated during the operation of the power tool and similar accelerating material particles.
In case the working tool 10 need be replaced, the cover device can be rapidly removed, without using any tools, by lightly disengaging the engaging-from-behind elements 24 from the shielding member 12 in order to be able to engage the tool-retaining element with the assembly tool 18.
Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A cover device for partially covering a front, in an axial direction, side of a disc-shaped working tool (10) of a power tool having a shielding member (12) that partially radially covers the working tool (10), the cover device comprising:

bearing means (22) securable on the shielding member (12) and having a bearing surface (28) abutting, at least regionwise, an outer surface (14) of the shielding member (12);

a protective disc (30) extending substantially transverse to the bearing surface (28) of the bearing means (22); and

engaging-from-behind elements (24) provided at opposite tangential ends of the bearing surface (28), respectively, at least one of the engaging-from-behind elements (24) being elastically pivotal in a radial direction for changing a distance (a) between the engaging-from-behind elements (24).

2. A cover device according to claim 1, wherein the engaging-from-behind elements (24) extend radially inward for engaging from behind tangential limiting edges (26) of the bearing surface (28) of the bearing means (22).

3. A cover device according to claim 1, wherein at least one of the engaging-from-behind elements (24) is formed as a form-stable hook-shaped element (32) connected with the bearing means (22), and wherein the protective disc (30) is provided with a slot (34).

4. A cover device according to claim 1, further comprising an elastically resilient locking element (40), and wherein at least one of the engaging-from-behind elements (24) is provided on the locking element (40).

5. A cover device according to claim 4, wherein the locking element (40) has a spring arm (42) and a locking nose (38) provided on a free end of the spring arm (42) and extending radially inward.

6. A cover device according to claim 5, wherein the spring arm (42) is formed by two, extending parallel to each other, cut-ins (44) provided on a tangential end of the bearing surface (28).

7. A cover device according to claim 1, wherein the cover device (20), together with the engaging-from-behind elements (24), is formed as a one-piece part.

8. A cover device according to claim 1, wherein the protective disc (30) extends at least over a half-circle defined by the bearing means (22).