PROTECTIVE ELEMENT FOR AN ELECTRIC POWER TOOL

Abstract

A protective element, in particular a cover, for the guard of a disk-shaped tool of an electric power tool, in particular an angle grinder. The protective element has a protective element body that is reversibly attached to the guard in an installed position by clamping the guard between attachment elements and a leaf spring of the protective element body. The invention also relates to a manufacturing method for the protective element and an electric power tool having this protective element.

Claims

1. A protective element for a guard of a disk-shaped tool of an electric power tool, in particular an angle grinder, the protective element being configured to be captively and reversibly connectable to the guard and to at least partially cover the tool, the protective element comprising: a protective element body; a first end and a second end opposite the first end; at least one attachment element mounted on the first end and is configured to be reversibly connectable to a guard edge of the guard during installation of the protective element on the guard; and a receiving device to receive a leaf spring, the receiving device being arranged on the second end, wherein the leaf spring is arranged in the receiving device and is configured such that the leaf spring is tensioned in an installed position of the protective element on the guard and the guard is clamped between the leaf spring and the at least one attachment element, wherein the receiving device includes two opposite regions with respect to a central axis of the protective element body, wherein each of the two opposite regions comprises: a clamping edge, wherein the leaf spring rests against the clamping edge in the receiving device when the protective element is installed; a contact section, wherein a distance between the two contact sections is less than a length of the leaf spring; and a transition edge that includes a transition from the receiving device to an inner circumference of the protective element body or to an inner circumference of an outer wall of the protective element body.

2. The protective element according to claim 1, wherein the leaf spring is brought into a first position in which the leaf spring has little tension or no tension, in which the protective element is removed and is spaced apart from the guard, and is brought into the installed position in which the protective element is captively and reversibly clamped to the guard via a clamping force of the leaf spring.

3. The protective element according to claim 1, wherein the protective element body has a rear wall and, opposite hereto, a wall, wherein a free space is defined below the wall in a direction of the rear wall, and wherein the free space is configured to permit the installation of the tool via a tilting.

4. The protective element according to claim 1, wherein the protective element body has an extension, wherein the extension is configured to surround the guard via which the installed protective element is held immovably.

5. The protective element according to claim 3, wherein the wall is arranged at an angle or an angle of 3, to the rear wall.

6. The protective element according to claim 1, wherein the attachment element permits an interlocking and/or frictional connection to the guard and or is hooklike in design.

7. The protective element according to claim 1, wherein the leaf spring is metallic, and, or, contains an austenitic material, in particular nickel-chromium steel 1.4310.

8. The protective element according to claim 1, wherein the deflection of the leaf spring in the installed position is accomplished in such a way that its center point is displaced radially outward toward an outer wall of the protective element body with respect to the tool axis.

9. The protective element according to claim 1, wherein the material of the protective element is chosen from the group of thermoplastics or polyamides or glass-fiber reinforced thermoplastics.

10. The protective element according to claim 1, wherein the protective element body is monolithic in design.

11. The protective element according to claim 1, wherein the leaf spring is an elongated part with a length that is several times greater than the maximum height of the component, in particular with a length between 40 and 100 mm, preferably between 60 and 80 mm.

12. The protective element according to claim 11, wherein the leaf spring has a deflection, or a deflection of between 2 mm and 6 mm, or has a deflection of 4.1 mm, when the protective element is installed on a guard.

13. An electric power tool, in particular angle grinder, comprising a protective element according to claim 1.

14. A method for producing the protective element according to claim 1, the method comprising: creating the protective element body by an injection molding method; and inserting the leaf spring into the receiving device of the protective element body.

15. The protective element according to claim 1, wherein the protective element is a cover.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0034] FIG. 1a shows the perspective view of a protective element according to the invention in accordance with an exemplary embodiment.

[0035] FIG. 1b shows a detail of the protective element from FIG. 1a.

[0036] FIG. 2 shows a section of a cross-sectional view of the protective element from FIG. 1a viewed perpendicularly to a tool axis.

[0037] FIG. 3 shows a detail of the view from FIG. 2.

[0038] FIG. 4 shows a cross-sectional view of the protective element from FIG. 1a viewed perpendicularly to a tool axis.

[0039] FIG. 4a shows a detail from FIG. 4.

[0040] FIGS. 5 and 6 each show a cross-sectional view of a protective element according to the invention viewed perpendicularly to a tool axis, according to two additional different exemplary embodiments.

[0041] FIG. 5a shows a detail from FIG. 5.

[0042] FIG. 6a shows a detail from FIG. 6.

[0043] FIG. 7 shows a perspective, side view of the protective element from FIG. 1a to be attached to a guard, in a representation sectioned parallel to the tool axis.

[0044] FIG. 8 shows a perspective, side view of the protective element from FIG. 1a attached to a guard, in a representation sectioned parallel to the tool axis, as well as a grinding wheel during the process of its installation on a spindle of an angle grinder.

[0045] FIG. 9 shows a cross-sectional view of the protective element from FIG. 8.

[0046] FIG. 10 shows the protective element from FIG. 1 in a front view.

DETAILED DESCRIPTION

[0047] FIG. 1a illustrates the perspective view of a protective element 100 according to the invention, also referred to as a cover. The protective element has a protective element body 18. The latter has, on its front, a wall 14facing upward in FIG. 1aand a further rear wall 16facing downward in FIG. 1aopposite thereto, wherein the wall 14 and the rear wall 16 are connected by an outer wall 17 that runs essentially parallel to the tool axis 50.

[0048] The protective element 100 is designed as a cover element in that it has the wall 14 serving as cover wall, with which a disk-shaped tool can be partially covered. The protective element 100 was developed in order to be safely and reversibly connected to a guard 30 and in so doing to cover at least a part of the disk-shaped tool and thus to protect a user or to avoid an undesirable action of the tool on a workpiece. The protective element body 18, which is part of the protective element 100, possesses a further specific structure: it has a section with a first end 10 and a section with a second end 20 opposite the first end. The first end 10 is therefore the open end shown in FIG. 1a and the second end 20 is the closed end of the protective element body 18 opposite thereto, wherein the ends are opposite one another along a radial direction M that runs perpendicular to the tool axis 50.

[0049] In addition, the present exemplary embodiment of the protective element 100 shows a first functional group with two attachment elements 11 that are mounted on the first end 10 of the protective element 100. These attachment elements 11 were designed to enter into a reversible connection with a guard edge 32 of the guard 30. A reliable attachment and covering of the tool by the protective element 100 and the guard 30 is ensured by this design of the protective element 100 in combination with a second functional group.

[0050] FIG. 1b illustrates the securing of the protective element 100 in accordance with the invention on a guard 30. Shown enlarged is the first functional group, which is positioned on the first end 10 of the protective element 100, accordingly on the guard edge 32, and which has multiple attachment elements 11, of which one is shown in FIG. 1b. In the exemplary embodiment shown, these attachment elements 11 are connected structurally seamlessly, in particular monolithically, to the protective element body 18, and are designed here as projections of an edge 13 of the protective element body 18 that faces in the direction of the first end 10. The arrangement and the shape of the attachment element 11 has the effect that an inner surface of the rear wall 16 of the protective element body 18 can rest against an outer surface of the guard 30 in contiguous contact.

[0051] The attachment element 11 serves as an end support. It is, in particular, a hook element, which here has an opening 12 facing in the direction of the protective element body 18. A protective element 100 preferably has two attachment elements 11. Alternatively, however, exactly one attachment element 11 or more than two attachment elements 11 can also preferably be provided.

[0052] In the exemplary embodiment shown, the attachment elements 11 are designed with a U-shaped or V-shaped opening 12. In the installed state, each attachment element 11 surrounds the guard 30 at its guard edge 32 and is tensioned in the direction of the guard 30 with the aid of a second function group. An interlocking and/or frictional connection between the guard 30 and the protective element 100 is produced with the aid of the first and second functional groups as a result.

[0053] The depicted opening 12 serves the purpose of facilitating effortless and safe installation of the protective element 100 by making possible simple mounting on the guard 30 or its guard edge 32. Each individual attachment element 11 has a specific length of approximately 15 millimetersmeasured along the guard edge 32in the exemplary embodiment shown, by which means an optimal securing of the protective element 100 is ensured. In addition, the attachment elements 11 were intentionally placed distant from the tool axis 50, shown in FIG. 2, in order to ensure stable and reliable attachment. This means in particular that an attachment element is positioned closer to an outer circumference of the protective element 100 than to a center of the protective element 100 through which the tool axis 50 passes in the installed position. This positioning contributes to increasing the structural strength of the protective element 100 in the installed position by making possible a sturdy connection to the guard 30.

[0054] In FIG. 2, the second functional group for attaching the protective element 100 to the guard 30 can be seen; this group is positioned at the second end 20 of the protective element 100, the end opposite the first end 10. This second functional group includes a receiving device 21 that is configured to receive a leaf spring 40 and that is specifically designed for the installation and the functionality of the leaf spring 40. The receiving device 21 in this case includes two clamping edges 22that are opposite with respect to a central axis M of the protective element 100and contact sections 23, which serve the purpose of correct installation and reliable insertion of the installed cover.

[0055] The contact section 23, which here is L-shaped in design, with the L shape being shown mirror-inverted in the upper region in the depicted exemplary embodiment, is placed in alignment with the tool axis 50 in each case. The distance A between the outermost edges 26 of the contact sections 23, which are perpendicularly opposite one another in the direction of the central axis M of the cover, is less than the length of the leaf spring 40 that is inserted into the receiving device 21. The distance X between the inner edges 27 of the contact sections 23, which are perpendicularly opposite one another in the direction of the central axis M of the cover, is greater than the length of the leaf spring 40 that is inserted into the receiving device 21. This configuration ensures that the leaf spring 40 can be inserted safely and without loss in the receiving device 21 by allowing reliable locking and secure seating.

[0056] The leaf spring 40 is strip-shaped, with a maximum dimension along its longitudinal extent. The dimensions of the leaf spring 40 are 7012.7>1 mm in the exemplary embodiment shown. The dimensions of the distances A and X and the length of the leaf spring 40 are determined such that the leaf spring 40 can be inserted into the receiving device 21 with play, which is to say loosely. When the leaf spring 40 is inserted, it is bent to a sufficient degree that its length is slightly shorter than the distance A, so that the leaf spring 40 can be inserted into the receiving device 21. In the installed state, when the protective element 100 is attached to the guard 30, the clamping edges 22 form contact points for the leaf spring 40.

[0057] FIG. 3 illustrates a transition edge 24 of the receiving device 21 to the inner circumference of the protective element 100. This depiction illustrates the region in which the receiving device 21 transitions into the inner circumference D of the protective element 100. This transition region formed by the transition edge 24 marks the section in which the structural elements of the receiving device 21 transition into the inner region of the protective element 100 in order to ensure a continuous and smooth connection that holds the leaf spring 40 as part of the second functional group.

[0058] FIG. 4 shows the exemplary structural component dimensions to accomplish a pull-off force, which here is realized by a specific deflection of 4.1 mm for the employed leaf spring 40 made of the material 1.4310. The material 1.4310 of the metallic leaf spring 40 here is a nickel-chromium steel with an austenitic structure, which is known as classic stainless spring steel on account of its good ductility and hardness.

[0059] The intended deflection of the leaf spring 40 is accomplished in the installed position in such a way that its center point is displaced radially outward toward the outer wall (17) of the protective element body (18) with respect to the tool axis (50). In particular, the deflection is accomplished such that, on the side facing the tool axis 50, the leaf spring 40 is bent away from the circumferential surface of the guard 30 toward the clamping edges 22. The positioning of the second functional group was determined accordingly in order to ensure a specific deflection of the leaf spring 40 of 4.1 mm. This deflection is provided in order to achieve the desired pull-off force in accordance with the specified requirements.

[0060] The market-determinant abrasive diameters are 115, 125, and 150 mm. In addition, other diameters of abrasives are also known, for example 100 mm, 180 mm, and 230 mm. Since the inner diameter of a protective element 100 corresponds essentially to the outer diameter of a corresponding guard 30, and this diameter or radius influences the deflection of the leaf spring 40, the second functional group is arranged as a function of the corresponding diameter.

[0061] As FIGS. 4 and 4a show, the distance s from the clamping edge 22 to the transition edge 24 in the case of a guard 30 for a tool disk with a diameter of 115 mm is approximately s=4.7 mm. This dimension describes the specific distance between the clamping edge 22 and the transition region 24, measured in a direction parallel to the central axis M, on the guard 30 with a specified length of 115 mm.

[0062] With respect to the protective element 200 from FIGS. 5 and 5a, the distance s between the clamping edge 22 and the transition edge 24 in the case of a guard 30 is approximately s=3.4 mm for a tool disk with a diameter of 125 mm. This statement describes the distance between the clamping edge 22 and the transition region 24, measured in a direction parallel to the central axis M, on a guard 30 with a specified length of 125 mm.

[0063] For the protective element 300 from FIGS. 6 and 6a, the distance s between the clamping edge 22 and the transition edge 24 along a guard 30 for a tool disk with a diameter of 150 mm is approximately s=2 mm. This statement describes the distance between the clamping edge 22 and the transition region 24, measured in a direction parallel to the central axis M, on a guard 30 that is designed for an abrasive with a diameter of 150 mm.

[0064] As is evident, the clamping edge 22 is positioned closer to the tool axis 50 with increasing diameter of the guard. These different arrangements are intended to achieve the requisite deflection of the leaf spring 40 of 4.1 mm with varying diameters of the guard 30. In this way, the necessary clamping force is generated in order to ensure the required pull-off force of 50 N according to the standard (DIN EN IEC 62841-2-3 (VDE 0740-2-3):2022-07, in particular Annex AA), and to do so independently of the diameter of the guard 30 or the grinding wheel.

[0065] The specification regarding the replacement of a grinding wheel while the protective element 100 is installed requires a height of the protective element 100 that is greater than that of the guard 30.

[0066] FIG. 7 displays a section through a protective element 100 that is mounted over an installed guard 30. It is evident that the protective element 100 has a free space F, which is located above the guard 30 in the exemplary embodiment shown.

[0067] It is made clear in FIG. 8 that the free space labeled F of an installed protective element 100 can be used in order to install a grinding wheel 30 or a comparable tool. A grinding wheel can be inserted at an angle into the guard 30 on the shaft of a power tool and fastened, using the free space F. On account of the free space F, this is possible with the protective element 100 installed.

[0068] To further facilitate installation of the protective element 100, the wall 14 of the protective element 100 that serves as cover wall 14 and that covers the grinding wheel in the outward axial direction is arranged at an angle of approximately 3 degrees together with the free space F in the exemplary embodiment shown.

[0069] In the exemplary embodiment shown in FIG. 9, an extension 15 is present on the protective element 100 that serves to keep the protective element 100 stable during operation by means of an interlocking contact. This extension 15 is placed at the height of the center line of the protective element 100 and is located at a distance from the rear wall 16 of the protective element 100. The extension 15 is dimensioned such that the protective element 100 is arranged immovably in operation of the power tool. In addition, the extension 15 is likewise arranged at an angle of approximately 3 degrees to the rear wall 16 in order to ensure that installation of the protective element 100 and a grinding wheel 31 is not adversely affected by the extension 15. The first wall 14, the cover wall, is opposite the rear wall 16. Both walls 14 and 16 have a slight inclination relative to a plane exactly perpendicular to the tool axis 50, wherein the wall 14 has a greater inclination than the rear wall 16. Both walls 14 and 16 therefore run only essentially perpendicular to the tool axis 50.

[0070] The rear wall 16 and the second wall 14 are monolithically connected by the outer wall 17. The extension 15, which runs in the circumferential direction around the tool axis 50, is provided in the transition region between the wall 14 and the outer wall 17. The outer wall 17 runs parallel to the tool axis 50. The protective element body 18 is an injection-molded part, in particular. The first wall 16 is shaped such that it rests flat against an outer wall of the guard 30 in the installed position of the protective element 100, wherein this outer wall extends nearly perpendicular to the tool axis.

[0071] FIG. 10 shows the rear wall 16 and the wall 14 of the protective element 100, which are connected by the outer wall 17, in a rear view. The outer wall 17, which runs concentrically around the tool axis 50 in the circumferential direction, has the receiving device 21 for the leaf spring 40. The rear wall 16 has essentially the shape of an annular segment, and here is essentially planar or nearly perpendicular to the tool axis 50. The annular segment is essentially one half of an annulus here. The wall 14, the front, also has essentially the shape of an annular segment, and is nearly perpendicular to the tool axis 50 here. The annular segment is essentially one half of an annulus here. In order to achieve a satisfactory covering function, the wall 14 extends farther radially inward toward the tool axis 50 than the rear wall 16 does. The maximum possible protection of the tool disk can be achieved in this way.

[0072] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.