CLAMPING DEVICE FOR FASTENING A TOOL DISC TO A POWER TOOL, POWER TOOL, AND FASTENING METHOD

Abstract

A clamping device for fastening a tool disc to a power tool, wherein the clamping device has a screw provided for being screwed into a drive spindle of the power tool in order to fasten the tool disc. The screw is mounted in a coupling module of the clamping device, wherein the coupling module has a first flange and an internal contour, wherein the clamping device gives rise to a form-fitting fastening of the tool disc to the power tool, and wherein the second flange prevents undesired loosening or tightening of the screw. A power tool having a drive spindle, to which a tool disc can be fastened by the proposed clamping device, and to a method for fastening a tool disc to such a power tool.

Claims

1. A clamping device for fastening a tool disc to a power tool, the clamping device comprising: a coupling module having a first flange and an internal contour; and a screw for screwing into a drive spindle of the power tool in order to fasten the tool disc, the screw being mounted in the coupling module; the first flange preventing an undesired loosing or tightening of the screw, the clamping device creating a form-fitting fastening of the tool disc to the power tool.

2. The clamping device as recited in claim 1 wherein the first flange has an opening, a base surface and a collar-like side wall.

3. The clamping device as recited in claim 1 wherein the screw has an operating element, a screw head, a thread, and a bearing surface for making contact with the first flange.

4. The clamping device as recited in claim 1 further comprising a second flange, the second flange, in a fastened state, being arranged between the drive spindle and the tool disc.

5. The clamping device as recited in claim 4 wherein the second flange has a bearing surface and a centering device.

6. The clamping device as recited in claim 1 wherein the first flange, in a fastened state, is arranged indirectly or directly between the tool disc and the screw.

7. The clamping device as recited in claim 1 further comprising a circlip arranged between the tool disc and the first flange.

8. The clamping device as recited in claim 1 wherein the internal contour is formed by a dihedron.

9. The clamping device as recited in claim 1 wherein the screw has a protruding region constituting a centering aid.

10. A power tool comprising: a drive spindle; and the clamping device as recited in claim 1; the drive spindle having, at an end, an internal thread connectable to the screw of the clamping device in order to fasten the tool disc to the drive spindle of the power tool.

11. The power tool as recited in claim 10 wherein the drive spindle is flattened on two sides.

12. The power tool as recited in claim 10 wherein the power tool is a cut-off grinder.

13. A method for fastening a tool disc to a power tool, the method comprising the following method steps: a) providing the clamping device as recited in claim 1; and b) screwing the screw into the drive spindle of the power tool, the screw being led through the internal contour and the first flange and through the tool disc.

14. The method as recited in claim 13 wherein the screw is screwed into an internal thread at an end of the drive spindle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further advantages emerge from the following description of the figures. The figures, the description and the claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them to form sensible further combinations.

[0031] In the figures, identical and similar components are denoted by the same reference signs.

[0032] In the figures:

[0033] FIG. 1 shows a view of a preferred embodiment of the fastening system,

[0034] FIG. 2 shows a view of a second preferred embodiment of the fastening system,

[0035] FIG. 3 shows a view of a further preferred embodiment of the fastening system,

[0036] FIG. 4 shows a view of a further preferred embodiment of the clamping device, wherein the screw has a protruding region as a centring aid.

DETAILED DESCRIPTION

[0037] The figures show preferred embodiments of the proposed fastening system. The fastening system illustrated in FIG. 1 comprises a clamping device 10, by means of which a tool disc 300 can be fastened or clamped by means of a coupling module 1 to a drive spindle 20 of a power tool 100 (illustrated solely schematically). The coupling module 1 has a first flange 17 and an internal contour 16. The internal contour 16 and the first flange 17 each have central openings through which a screw 2 can be led. The screw 2 has a screw head 12, an external thread 14 and a bearing surface 9. The clamping device 10 furthermore has an operating element 3, which may be arranged on the screw head 12 and which is therefore referred to in the context of the present invention either as operating element of the clamping device or as operating element of the screw. The operating element 3 may be in the form of a knob or a grip. The user of the power tool 100 can grip and rotate the operating element 3 such that the tool disc 300 of the power tool 100 can be released or tightened, without the use of tools, using the operating element 3 of the clamping device 10.

[0038] The first flange 17 has a central opening 4 for the leadthrough of the screw 2 and has a base or bottom surface 5. The base surface 5 is preferably substantially circular, such that the outer edge of the first flange 17 forms a substantially circular circumference. A side wall 6 may extend at the circumference of the first flange 17, which side wall forms a collar of the first flange 17 and has the effect that the first flange 17 is of pot-shaped design.

[0039] This embodiment of the invention is illustrated in FIG. 2 where the leftmost image shows the first flange 17 and operating element 3 together in a perspective view and the second leftmost image a cross-section view with the remaining images being an exploded view. The embodiment of the invention illustrated in FIG. 2 may be used in particular for diameters of 60 millimetres (mm), that is to say, for example, for steel bonded diamond cut-off discs 300. The base surface 5 of the first flange 17 may alternatively protrude beyond the side wall 6. This embodiment of the invention is illustrated in FIG. 3. The embodiment of the invention illustrated in FIG. 3 may be used in particular for diameters of 90 or 100 mm, that is to say, for example, for abrasive discs 300 for relatively large cut-off grinders 100. The diameter specifications given here preferably relate to the diameter of the flanges 8, 17, with the flange diameters arising from a predefined ratio of diameter of the tool disc 300 to diameter of the flange 8, 17. Such a ratio may for example be 0.25 and obtained from approval standards or the like. For abrasive discs having a diameter of 350 mm, a predefined ratio of 0.25 may for example yield a flange diameter of at least 87.5 mm. Such a flange diameter may for example be rounded up to 90 mm. In the context of the invention, it may also be preferred that the flange diameter is dependent on a gear head size. This preferably applies in particular to tool discs 300 consisting of steel or to tool discs 300 comprising steel.

[0040] By means of these measures or design embodiments of the first flange 17, it can be achieved that the operating element 3 of the clamping device 10 is shielded with respect to the tool disc 300. In this way, contact between an underlying surface and the operating element 3 of the clamping device 10 can be prevented, and it can be ensured that the screw 2 of the clamping device 10 does not unintentionally loosen during the operation of the power tool 100, or thatin the case of an opposite direction of rotation of the tool disc 300the screw 2 does not tighten such that it is virtually unreleasable.

[0041] The internal contour 16 of the coupling module 1 or of the clamping device 10 may be designed as a tool-free nut and comprise an M8 thread. The internal contour 16 may in particular be designed as a dihedron, wherein the screw 2 can be mounted in an interior 15 of the internal contour 16. The screw 2 may be somewhat longer than the outer walls of the internal contour 16, such that the screw 2 protrudes out of the interior 15 of the internal contour 16. The screw 2 can then advantageously also be used as a centring aid. A pin 18 may also be provided, as a further centering aid, on the end of the screw 2. This embodiment of the invention is illustrated in FIG. 4. The screw 2 can be led through the opening 4 in the first flange 17 and through a central opening in the tool disc 300. The screw 2 can then be screwed into an internal thread 22 of the drive spindle 20 of the power tool 100 (see FIG. 1). The tool discs 300 can thus be axially clamped to the drive spindle 20. A circlip 7 may be provided between the first flange 17 and the tool disc 300.

[0042] A second flange 8 may be provided between the drive spindle 20 and the power tool 100. The second flange 8 has a central opening which, in the context of the invention, can preferably be referred to as a centering means 13. Furthermore, the second flange 8 may have a bearing surface 11 that is in contact with the tool disc 300 when the tool disc 300 is fastened to the power tool 100. The second flange 8 may also have a rotational driving means designed for example as a dihedron or as a hexagon.

[0043] FIG. 4 shows a preferred embodiment of the clamping device 10, wherein the screw 2 has a protruding region 18 as a centring aid. The protruding region 18 may for example be designed as a pin. Also illustrated in FIG. 4 are the thread 14 of the screw 2 and the operating element 3 of the clamping device 10 or of the screw 2. FIG. 4 also shows the outer flange 17 and the internal contour 16.

LIST OF REFERENCE SIGNS

[0044] 1 Coupling module [0045] 2 Screw [0046] 3 Operating element [0047] 4 Opening in the first flange [0048] 5 Base surface of the first flange [0049] 6 Side wall of the first flange [0050] 7 Circlip [0051] 8 Second flange [0052] 9 Bearing surface of the screw [0053] 10 Clamping device [0054] 11 Bearing surface of the second flange [0055] 12 Head of the screw [0056] 13 Centring means of the second flange [0057] 14 Thread of the screw [0058] 15 Interior of the internal contour [0059] 16 Internal contour [0060] 17 First flange [0061] 18 Protruding region as centring aid [0062] 20 Drive spindle [0063] 22 Internal thread of the drive spindle [0064] 100 Power tool [0065] 300 Tool disc of the power tool