Hand-held power tool with clamping nut

Abstract

A hand-held power tool with a drive spindle (2) which can be driven to rotate about a rotary axis (A), on which a clamping flange (3) and a clamping thread (4) for fixing a disc-shaped tool (5) via a clamping surface (6) of a clamping nut (7) which can be clamped on the clamping thread (4) are formed at the end, characterized in that a locking spring (9) which is radially pre-tensioned against the clamping thread (4) is arranged axially between the tool (5) and an inner projection (8) of the clamping nut (7), which forms at least one radially outwardly projecting nose (10) to which at least one radially inwardly open, axially extending groove (11) is assigned in the disc-shaped tool (5).

Description

[0001] The invention describes a hand-held power tool with a clamping nut for securing a disc-shaped tool, in particular an angle grinder, a hand-held stone saw or a hand-held circular saw.

[0002] Conventional tool holders for disc-shaped tools (which, in addition to flat discs, also include plate-shaped tools) clamp the tool to the driving spindle by frictional clamping between a clamping flange and a clamping nut screwed onto the drive spindle. The thread direction of the clamping thread on the drive spindle is usually chosen so that the clamping nut tightens automatically when the power tool is switched on or the tool is attached.

[0003] Modern hand-held power tools with safety routines allow the work spindle to be braked suddenly to a standstill. To reliably prevent the clamping nut or the disc-shaped tool from unintentionally detaching from the drive spindle even if it has loosened due to inertia during the sudden spindle stop, an additional clamping device is arranged in addition to the clamping nut, according to DE4238466. This additional clamping device presses against the disc-shaped tool and is preloaded against the clamping nut by a disc spring.

[0004] According to DE 42 43 328 C1, the additional clamping device is designed to be rotationally fixed to the drive spindle and thus brakes the inertia-induced relative rotation of the clamping nut.

[0005] According to DE 43 05 317 A1, this braking device is designed as a steel spring ring arranged in the clamping nut, which rubs against the clamping thread of the drive spindle. Another hand-held power tool of this type is shown in DE 42 38 466 C1.

[0006] The object of the invention is to realize a further secure tool holder for a disc-shaped tool with a clamping nut.

[0007] The problem is essentially solved by the features of claim 1. Advantageous further developments result from the dependent claims.

[0008] A hand-held power tool with a drive spindle that can be driven to rotate about a rotary axis has at its end a clamping flange and a clamping thread for fixing a disc-shaped tool via a clamping surface of a clamping nut that can be clamped on the clamping thread, wherein a locking spring radially pre-tensioned against the clamping thread is arranged axially between the tool and an inner step of the clamping nut, which forms at least one radially outwardly projecting nose, to which at least one radially inwardly open, axially extending groove is assigned in the disc-shaped tool.

[0009] Due to the radially projecting nose of the locking spring, which is frictionally fixed to the clamping thread, the disc-shaped tool can only be removed from the drive spindle in specific, circumferentially defined positions, and in particular not in a state where it is rotating relative to the drive spindle due to inertia. Thus, even if the clamping nut were to detach from the drive spindle due to inertia, the disc-shaped tool would remain axially fixed to the drive spindle.

[0010] The safety spring is advantageously made of spring steel, which makes it highly elastic.

[0011] Advantageously, the locking spring is made of wire, which makes it technically easy to manufacture.

[0012] The locking spring is advantageously designed as an almost completely circumferential spring ring, which results in high static friction.

[0013] Advantageously, the locking spring has two diametrically opposed, outwardly projecting lugs, which allows an associated disc-shaped tool to be ergonomically mounted / dismounted in at least two circumferential positions.

[0014] The invention is explained in more detail with regard to an advantageous embodiment by: Fig. 1 as a hand-held power tool with clamping nut in longitudinal section Fig. 2 as a detail Fig. 3 as Fig. 1 in axial view with the clamping nut detached

[0015] After Fig. Figure 1 shows a (only indicated) hand-held power tool 1 with a drive spindle 2 driven to rotate about a rotary axis A, a positively locking clamping flange 3 and a clamping thread 4 at the end of the spindle. To secure a disc-shaped tool 5 in the form of a grinding wheel, it is clamped via a clamping surface 6 of a clamping nut 7 clamped onto the clamping thread 4. A locking spring 9 made of spring steel, radially pre-tensioned against the clamping thread 4, is arranged axially between the tool 5 and an internal recess 8 of the clamping nut 7.

[0016] After Fig. 2 The retaining spring 9 forms, in the form of a spring ring made of bent spring steel wire, which is almost completely circumferential, two diametrically opposed, radially outwardly projecting noses 10.

[0017] In the after Fig.The disc-shaped tool 5 is associated with two diametrically opposed, radially inwardly open, axially extending grooves 11 corresponding to these lugs 10. In the indicated state, in which the disc-shaped tool 5 rotates freely about the axis of rotation A due to inertia, the grooves do not coincide with the lugs 10 in the vast majority of angular positions (as shown), thus axially locking the disc-shaped tool 5 to the stationary drive spindle 2.

Claims

[1] Hand-held power tool with a drive spindle (2) which can be driven to rotate about a rotary axis (A) and on which a clamping flange (3) and a clamping thread (4) are formed at the end for fixing a disc-shaped tool (5) via a clamping surface (6) of a clamping nut (7) which can be clamped on the clamping thread (4), characterized by , that axially between the tool (5) and an inner step (8) of the clamping nut (7) a locking spring (9) is arranged which is radially preloaded against the clamping thread (4) and which forms at least one radially outwardly projecting nose (10) to which at least one radially inwardly open, axially extending groove (11) is assigned in the disc-shaped tool (5). [2] Hand-held power tool according to claim 1, characterized by , that the locking spring (9) is made of spring steel. [3] Hand-held power tool according to claim 1 or 2, characterized by , that the retaining spring (9) is made of wire. [4] Hand-held power tool according to any one of claims 1 to 3, characterized by , that the retaining spring (9) is designed as an almost completely circumferential spring ring. [5] Hand-held power tool according to any one of claims 1 to 4, characterized by , that the locking spring (9) has two opposing, outwardly projecting noses (10).

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