Securing Device

Description

PRIOR ART

Fastening devices for attaching a grinding disc to an angle grinder have already been proposed. These comprise a fastening sleeve, which presses the grinding wheel directly against a carrier plate.

DISCLOSURE OF THE INVENTION

The invention proceeds from a fastening device for fastening a grinding and/or polishing disc to a tool holder, in particular a tool holder of an angle grinder, having at least one carrier plate for holding and/or supporting the grinding and/or polishing disc, which preferably comprises a through-hole, preferably a central through-hole, and having a tensioning sleeve for inserting into the through-hole and for establishing a frictional connection between the grinding and/or polishing disc and the carrier plate.

It is proposed that the fastening unit comprises at least one intermediate element for disposing between the tensioning sleeve and the grinding and/or polishing disc to strengthen the frictional connection.

A good hold can be achieved for the grinding disc and/or polishing disc with the embodiment of the fastening device according to the invention.

A “grinding and/or polishing disc” is to be understood in particular a consumable material that is intended to be set into motion by a power tool comprising the tool holder, in particular a power hand tool, in motion. The grinding and/or polishing disc may in particular comprise a flexible carrier material onto which a grinding and/or polishing agent, in particular a material of high hardness and/or low grain, is applied. Alternatively, the entire grinding and/or polishing disc may be formed from the same material. The surface of a part, for example, may be ground and/or polished using the grinding and/or polishing disc. The grinding and/or polishing disc may be configured as a fiber disc and comprise, for example, a fibrous material as a carrier material. The power tool may be provided to set the grinding and/or polishing disc into a rotating and/or oscillating motion, particularly about an axis of motion that passes through the through-hole and/or is perpendicular to at least a majority of the grinding and/or polishing disc.

The carrier plate may, for example, be at least largely formed from a rubber or a rubber-like material. The tensioning sleeve is advantageously provided for securing, in particular tensioning, at least the carrier plate to the tool holder. The carrier plate may comprise a positive locking element provided to interact with a positive locking element of the tool holder in order to establish a rotationally fixed connection between the tool holder and the carrier plate, in particular with respect to the axis of movement. Alternatively, the carrier plate can be fixed to the tool holder with respect to a rotating and/or oscillating movement about the axis of movement solely by means of friction, in particular by means of the tensioning sleeve.

Preferably, the grinding and/or polishing disc is formed from a flexible material. The intermediate element may be provided to partially deflect and/or deform the grinding and/or polishing disc. The intermediate element may deflect the grinding and/or polishing disc or a portion thereof such that the intermediate element extends to below a grinding surface formed by the grinding disc. The intermediate element may partially rest on the grinding surface. For example, the grinding surface is defined by a surface of the carrier plate surrounding the through-hole. Preferably, the grinding and/or polishing disc lies flat and/or level on the carrier plate to form the grinding surface.

For example, the tensioning sleeve and/or intermediate element are provided to positively fix the grinding and/or polishing disc and/or the carrier plate to the tool holder with respect to directions along the axis of movement. The tensioning sleeve may be manufactured from a different material than the intermediate element. The tensioning sleeve is preferably formed from a metal, in particular aluminum, tool steel or stainless steel. The tensioning sleeve advantageously has a hollow, cylinder-like shape.

According to further embodiments, the tensioning sleeve may have an interface for the purpose of forming a tool-free positive locking connection with the tool holder. For example, the tool holder is configured as an X-lock tool holder. In particular, a quick tool assembly and/or a quick replacement of the grinding and/or polishing disc may be achieved.

The intermediate element is advantageously annular and surrounds the tensioning sleeve. This can in particular can achieve high level of durability. According to an alternative, the fastening device can comprise, for example, a plurality of intermediate elements arranged at different points around the tensioning sleeve.

Furthermore, it is proposed that the intermediate element is formed from a deformable material. In particular, the intermediate element is provided to adapt its shape to unevenness in the grinding and/or polishing disc. Advantageously, the at least one intermediate element is formed from rubber or a rubber-like material. In particular, a high reinforcement of the frictional lock may be achieved.

Further, the intermediate element and the carrier plate may each comprise a contact surface for clamping the grinding and/or polishing disc between the contact surfaces. In particular, a good frictional lock may be achieved.

Preferably, the contact surfaces comprise cones that are complementary to one other. Two parts having “complementary” cones should be understood to mean that both parts each have a cone and that, when the two parts are assembled together, the cone of the one part lies flush and on a large surface against the cone of the other part. For example, the contact surface of the carrier plate surrounds the through-hole and is in turn surrounded by the grinding surface. The contact surface of the carrier plate may comprise such a cone, so that points of the contact surface are further away from a grinding plane in which the grinding surface lies, the closer they are to the through-hole. In particular, a large contact surface and a good frictional connection can be provided.

Further, the tensioning sleeve may have a radial protrusion at an external end for transferring a holding force from the tensioning sleeve to the intermediate element and/or the grinding and/or polishing disc. In particular, a high transmission of force may be achieved. Advantageously, the intermediate element is configured as separate from the tensioning sleeve. The intermediate element may have a groove in which the radial protrusion engages.

According to alternative embodiments, the tensioning sleeve can be configured without a radial protrusion and the at least one intermediate element can be fixed to an external end of the tensioning sleeve in a material-locking fashion, in particular by gluing.

Furthermore, it is proposed that the radial protrusion and the intermediate element have complementary cones with respect to each other.

Further, the cone of the contact surfaces may be steeper than the cone between the intermediate element and radial protrusion. The steeper the cone, the smaller a cone angle is between a straight line of the cone and the axis of movement, wherein the straight line of the cone intersects the axis of movement and runs parallel to a surface comprising the cone. Preferably, the contact surfaces comprise a cone that has a constant cone angle around the axis of movement. Advantageously, the tensioning sleeve and the intermediate element comprise a cone that has a constant cone angle around the axis of movement. According to alternative embodiments, it is contemplated that the cone angles of the cones are different around the axis of movement.

Furthermore, a power tool, advantageously a hand tool, in particular an angle grinder, is proposed comprising a fastening device described above.

The fastening device according to the invention and the hand tool according to the invention are not intended to be limited to the application and embodiment described above. In particular, the fastening device according to the invention and the hand tool according to the invention may have a number of individual elements, components and units that differs from a number specified herein in order to fulfill a function described herein. Moreover, regarding the ranges of values indicated in this disclosure, values lying within the limits specified hereinabove are also intended to be considered as disclosed and usable as desired.

DRAWINGS

Further advantages follow from the description of the drawings below. An exemplary embodiment of the invention is shown in the drawing. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will appropriately also consider the features individually and combine them into additional advantageous combinations.

The figures show:

• • a diagram of a power tool according to the invention having a fastening device according to the invention in a disassembled state,
  • a schematic cross-sectional view of the fastening device according to FIG. 1 in a mounted state, and
  • a tensioning sleeve of the fastening device in a schematic perspective view from below in a disassembled state.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

FIG. 1 shows a power tool 10 having a tool holder 12 and a fastening device 14 for attaching a grinding and/or polishing disc 20 to the tool holder 12. The power tool 10 is configured as a power hand tool. The power tool 10 is configured as an angle grinder.

The fastening device 14 comprises a support plate 16 for holding and/or supporting the grinding and/or polishing disc 20. The carrier plate 16 comprises a through-hole 17. The fastening device 14 further comprises a tensioning sleeve 18 for inserting into the through-hole 17 and for producing a frictional lock between the grinding and/or polishing disc 20 and the carrier plate 16. A diameter of the through-hole 17 is chosen just large enough to allow the tensioning sleeve 18 to be inserted flush.

The fastening device 14 comprises an intermediate element 22 for disposal between the tensioning sleeve 18 and the grinding and/or polishing disc 20 to reinforce the frictional connection.

The carrier plate 16 defines a grinding plane 24 (cf. FIG. 2). The grinding and/or polishing disc 20 abuts the grinding plane 24 in a working area of the carrier plate 16. The carrier plate 16 is largely formed of rubber and may have grooves and/or shafts in the working area, in particular to achieve changing contact pressures during a working operation and/or to produce an improved frictional connection with the grinding and/or polishing disc 20. The carrier plate 16 may have a metal base on a side facing the tool holder 12 in the assembled state in order to achieve a better hold on the tool holder 12.

The grinding and/or polishing disc 20 comprises a through-hole 17′. The tensioning sleeve 18 is provided for insertion through the through-hole 17′. The through-hole 17′is configured just large enough that the tensioning sleeve 18 can be inserted flush, so that the grinding and/or polishing disc 20 is centered on the carrier plate 16 when mounted on the carrier plate 16 and/or the tool holder 12. The grinding and/or polishing disc 20 comprises slots 21 extending radially from the through-hole 17′. The slots 21 permit deformation of the grinding and/or polishing disc 20 out of the grinding plane 24.

The intermediate element 22 may deflect the grinding and/or polishing disc 20 and/or at least a portion of the grinding and/or polishing disc 20 between the slots 21 such that the intermediate element 22 and the tensioning sleeve 18 lie outside the grinding plane 24.

The tensioning sleeve 18 comprises an interface 19 for completing a tool-free positive locking connection with the tool holder 12 (cf. FIG. 3).

The intermediate element 22 is annular and surrounds the tensioning sleeve 18. The intermediate element 22 is formed from a deformable material. The intermediate element 22 is formed from rubber.

The intermediate element 22 and the carrier plate 16 each have a contact surface 26, 26′ for clamping the grinding and/or polishing disc 20 between the contact surfaces 26, 26′. The contact surface 26 of the carrier plate 16 is disposed between the work area and the through-hole 17. The contact surfaces 26, 26′have cones that are complementary to one other.

The tensioning sleeve 18 has a radial protrusion 28 at an external end for transferring a holding force from the tensioning sleeve 18 to the intermediate element 22 and/or the grinding and/or polishing disc 20.

The radial protrusion 28 and the intermediate element 22 have cones 30, 30′that are complementary to one other. The cone of the contact surfaces 26, 26′is steeper than the cone 30, 30′between intermediate element 22 and the radial protrusion 28.