Clamping device and hand-held power tool

Description

[0001] The present invention relates to a clamping device for axially clamping a tool disc to a flange associated with a drive spindle of a hand-held power tool. The clamping device has a screw which, in order to clamp the tool disc securely, is screwed into an internal thread of the drive spindle.

[0002] Such clamping devices are generally known from the prior art. Clamping devices with a clamping nut, particularly designed as a two-hole nut, which are fastened to the drive spindle with a suitable tool, are also known from the prior art. However, the present invention relates to a different class of clamping devices, namely those comprising a screw that is screwed into an end-end internal thread of the drive spindle.

[0003] The object of the present invention is to create a clamping device that counteracts self-loosening of the clamping device - and thus a loosening of the tool disc during operation of the hand-held power tool.

[0004] For example, EP 3 202 533 A1 discloses a clamping device for axially clamping a disc-shaped tool, wherein the tool can preferably be a cutting disc. The clamping device of EP 3 202 533 A1 comprises a first and a second locking element, wherein the first locking element of the clamping device is rotatable relative to a screw and rotationally fixed to the clamping disc.

[0005] The problem is solved by the features of claim 1, and in particular by the fact that the screw is mounted in a coupling module of the clamping device, wherein the coupling module has an inner contour that is positively locked to the drive spindle in the circumferential direction and is rotationally secure. The clamping device has a disc spring which is configured to seal a grease chamber between a head of the screw and a collar of the coupling module and / or to axially preload a hand knob which is positively locked to the screw in the circumferential direction and is rotationally secure.

[0006] The clamping device according to the invention has the advantage that it cannot tighten or loosen during operation of the hand-held power tool, because the coupling module, as part of the clamping device, is positively locked and rotationally secured to the drive spindle. This is the counterpart to a flange that is preferably positively locked and rotationally secured to the drive spindle.

[0007] It has proven advantageous if the inner contour of the coupling module is designed as a hexagonal profile. Preferably, a corresponding outer contour of the drive spindle is designed as an external hexagon. Alternative positive-locking, rotationally secure pairings, for example in the form of a positive-locking shaft-hub connection, can be used.

[0008] Preferably, the internal thread of the drive spindle is an end-face internal thread. The internal thread may be recessed axially relative to a head face of the drive spindle. Preferably, the screw extends axially beyond the coupling module, particularly beyond the cylindrical section of the coupling module.

[0009] The coupling module is preferably cylindrical. Preferably, the coupling module has a cylindrical section that can project through a central opening in the tool disk. The cylindrical section of the coupling module can project into a central opening in the flange.

[0010] The clamping device features a handle knob that is positively locked to the screw in the circumferential direction, preventing rotation. This allows for particularly easy handling of the clamping device. No additional assembly tool, such as a wrench, is required.

[0011] In a particularly preferred embodiment, the clamping device has a clamping element that can be subjected to an axial clamping force by means of the coupling module in order to clamp the tool disc against the flange. The clamping element is particularly preferably designed as a spring plate. The spring plate can be disc-shaped.

[0012] The screw is mounted in the coupling module via a rolling bearing. Because the rolling bearing reduces head friction of the clamping element, an increased clamping force of the clamping device is achieved.

[0013] The rolling bearing is preferably designed as an angular contact ball bearing. The angular contact ball bearing preferably has a contact angle between 35° and 45°. The contact angle can be 40°. Due to the diagonal contact angle of the rolling elements, particularly in an angular contact ball bearing, the clamping device wedges itself radially towards the end of the clamping process. This provides increased security against unintentional loosening.

[0014] If the clamping device has a clamping element in the form of a spring sheet, which is preferred, the clamping device has increased insensitivity to settling, since the spring sheet is in frictional contact with the tool disc, which compensates for thermal expansions.

[0015] Furthermore, a clamping device is disclosed which includes an elastomer ring that is preferably arranged between a screw head and a collar of the coupling module. Alternatively or additionally, the clamping device can include a retaining ring by means of which the coupling module is held on the screw.

[0016] According to the invention, a disc spring is provided instead of the elastomer ring. The disc spring can serve to seal a grease gap between the screw head and the collar of the coupling mechanism. In addition, the disc spring can also axially preload the hand knob.

[0017] According to another advantageous embodiment, it is also possible to use a combination of elastomer element and mechanical spring instead of the elastomer ring.

[0018] It has proven advantageous to hold the tension member to the coupling module by means of a retaining ring.

[0019] In a further preferred embodiment, the clamping device has a stop by which the deflection of the clamping element is directly or indirectly limited. Preferably, the stop is designed as an annular collar and is arranged between the spring plate and the tool disc to be held. If the tool disc comes into contact with the stop during the clamping process, the axial deflection of the spring element is limited.

[0020] The problem is also solved by a hand-held power tool according to claim 8, preferably in the form of a grinder or cut-off grinder, with a drive spindle having a preferably end-end internal thread, and with a clamping device of the type described above. The drive spindle has an outer contour that is or can be coupled to the inner contour of the coupling module in a form-fit, rotationally secure manner in the circumferential direction.

[0021] It has proven advantageous if the hand-held machine tool includes a flange that is positively connected or connectable to the drive spindle in the circumferential direction by means of an anti-rotation device.

[0022] The hand-held power tool according to the invention can be advantageously further developed by means of the features described with reference to the clamping device.

[0023] Further advantages will become apparent from the following description of the figures. The figures illustrate various embodiments of the present invention. The figures, the description, and the claims contain numerous features in combination.

[0024] In the figures, identical and similar components are numbered with the same reference symbols. They show: Fig. 1 a preferred embodiment of a clamping device according to the invention together with a tool disc and a hand-held power tool; Fig. 2 the clamping device of the Fig. 1 front and back view; Fig. 3 the clamping device of the Figuren 1 and 2 in exploded view; Fig. 4 the clamping device of the preceding figures in sectional view; Fig. 5 a second embodiment of a clamping device according to the invention in partial section; and Fig. 5a a third embodiment of a clamping device according to the invention in partial section. Ausführungsbeispiele:

[0025] A preferred embodiment of a clamping device 10 according to the invention is shown in Fig. 1 The clamping device 10 is used to clamp a tool disc 300 in the axial direction AR. The tool disc 300 is to be clamped between the clamping device 10 and a flange 30, the flange 30 being associated with a drive spindle 20 of a hand-held power tool 100.

[0026] The flange 30 has an anti-rotation device 24 in the form of a lateral recess, so that the flange placed on the drive spindle 20 is positively connected to the drive spindle 20 in the circumferential direction U in a rotationally secure manner.

[0027] Again Fig. 1 The clamping device 10, which can be removed, has a screw 2 that is screwed into an end-end internal thread 22 of the drive spindle 20 to clamp the tool disc 300. On the underside of the clamping device 10, a coupling module 1 of the clamping device 10, provided according to the invention, is already partially visible, in which the screw 2 is centrally mounted. The internal contour according to the invention will be described later with reference to Fig. 2 explained in more detail.

[0028] Again Fig. 1 The clamping device 10 has a handle 3, which can be removed from the internal thread 22. This handle is used to manually screw the screw 2 into the internal thread 22 and thus to axially clamp the tool disc 300 between the clamping device 10 and the flange 30. The handle 3 is formed with the screw 2 in a form-fitting, rotationally secure manner in the circumferential direction U. For this purpose, the head of the screw 12 has, for example, an outer hexagonal contour that is embedded in a corresponding hexagonal inner contour of the handle 3. However, almost any other suitable contour can be used as an alternative to the hexagonal contour.

[0029] Again Fig. 1 As can be seen below, the drive spindle 20 has an outer contour, which in this example is designed as a hexagonal profile. An inner contour of the coupling module 1, not shown here, can be positively coupled to this outer contour 26. A positively locked, rotationally secure coupling between the coupling module 1 and the outer contour 26 is achieved when the clamping device 10 is clamped, whereby the coupling module 1 projects at least partially through a central opening 301 of the tool disk 300.

[0030] Fig. 2 The clamping device 10 now shows the Fig. 1 top view ( Fig. 2A ) as well as in bottom view ( Fig. 2B ).

[0031] Clearly recognizable in Fig. 2A The previously described hand knob 3, in which the screw 2 is positively locked in the circumferential direction by means of its head 12, is secured against rotation. The clamping device 10 also has a clamping element, which here is exemplified as a plate-shaped spring plate 4. The actual clamping force is applied to the tool disc 300 by means of the spring plate 4.

[0032] In Fig. 2B The central screw 2 of the clamping device 10 is clearly visible. The screw is mounted in the coupling module 1 of the clamping device 10; more precisely, the screw 2 is mounted coaxially in the coupling module 1. A cylindrical section 13 of the coupling module 1 is clearly visible, whereby the cylindrical section 13, when the tool disc 300 is clamped, at least partially passes through the central opening 301 of the tool disc 300 (see figure). Fig. 1 ) proceeds.

[0033] According to the invention, the coupling module 1 has an inner contour 16 which is positively locked against rotation in the circumferential direction UR with the drive spindle 20 (cf. Fig. 1 ) can be paired. According to the preferred embodiment shown, the inner contour 16 is designed as a hexagonal profile.

[0034] Fig. 3 Figure 10 now shows the preferred embodiment of the clamping device 10 from the preceding figures in an exploded view. In the upper area of ​​the Fig. 3 The screw 2 can be seen with its screw head 12, which has an external hexagonal contour as an example. In the lower area, a thread 14 of the screw 2 can be seen, which engages in an internal thread (cf. Fig. 1 The screw 2 is to be screwed into the internal thread 22. The screw 2 is mounted in the coupling module 1 via a rolling bearing, preferably an angular contact ball bearing 5.

[0035] An elastomer ring 6 shown below the hand knob 3 serves, among other things, to hold the outer contour of the screw head 12 within a corresponding inner contour of the hand knob 3. This is particularly evident from the Fig. 4 Visible below the elastomer ring 6 is the coupling module 1, which, in addition to the already described cylindrical section 13 and the hexagonal inner contour 16, also has a collar 11. The collar 11 is designed and intended to transmit a clamping force applied via the hand knob 3 and the screw 2 to the spring plate 4.

[0036] The coupling module 1 is positively locked and rotationally secure to the spring plate 4 in the circumferential direction U, and is coupled in the assembled state. This preferably applies to all embodiments. For this purpose, the coupling module 1 has a module contour 19 below the collar 11 of the coupling module 1, which corresponds to an inner contour of the spring plate 4. By way of example, the module contour 19 is designed as an outer square. A retaining ring 7 can be seen below the coupling module 1, by means of which the coupling module 1 is held on the screw 2.

[0037] The tensioning element, here in the form of the spring plate 4, is held on the coupling module 1 by means of a retaining ring 8. The function of the tensioning device 10 according to the invention shall now be described with reference to Fig. 4 will be explained in more detail.

[0038] First, if necessary, the flange 30 (see Fig. 1 The flange 30 is placed on the drive spindle 20 of the hand-held power tool 100. The anti-rotation device 24 secures the flange 30 to the drive spindle 20 in a positive-locking, rotationally secure manner in the circumferential direction U. The cutting disc 300 is then inserted. When the clamping element 10 is attached, the inner contour 16 (in this case, an internal hexagon socket) first engages with the outer contour 26 of the drive spindle 20 in a positive-locking, rotationally secure manner. Preferably, this occurs before the thread 14 of the screw 2 engages with the internal thread 22 of the drive spindle 20.

[0039] When the clamping device 10 is tightened, a hand force is transmitted to the screw 2 via an operating element, for example designed as a hand knob 3. This is achieved by the fact that the head 12 of the screw 2 is positively locked and rotationally secured in the hand knob 3 in the circumferential direction. At the latest when the spring plate 4 rests on the tool disc 300, the head 12 of the screw 2 slides over the angular contact ball bearing 5 relative to the coupling module 1 until radial tension is present at the end of the spring travel of the spring plate 4. This results in both axial and radial tension between the head 12 of the screw 2 and the coupling module 1, with the radial tension in particular generating the stronger holding force. The radial tension is achieved by designing the preferably provided rolling bearing as an angular contact ball bearing 5, which, for example, has a contact angle BW of 40° (see also Fig. 5 ). This increases head friction on the screw head 2, which prevents unintentional loosening of the clamping device 10.

[0040] The elastomer ring 6, located between the coupling module 1 and the head 12 of the screw 2, presses a section of the knob 3 against the screw head 12, thus preventing lubricant from leaking out of the rolling element chamber. Furthermore, the elastomer ring 6, in conjunction with the retaining ring 7, holds the coupling module 1 to the screw 2. A retaining ring 8, shown below the spring plate 4, serves to hold the clamping plate 4 to the coupling module 1.

[0041] Again Fig. 4 The clamping force, which can be extracted, is transferred in the axial direction AR via a collar 11 of the coupling module 1 to the spring plate 4 and from there to the tool disc 300. With respect to the circumferential direction UR, the spring plate 4 and the coupling module 1 are positively coupled to each other in a rotationally secure manner.

[0042] Fig. 5 Finally, another preferred embodiment of a clamping device 10 according to the invention is shown. Here, too, a rolling bearing in the form of an angular contact ball bearing 5 is provided between coupling module 1 and screw 2, which has a contact angle BW of 40° (by way of example). In contrast to the one described with reference to Fig. 4 The described embodiment features the embodiment of Fig. 5 a stop 9, by which a deflection of the tension member, which here is designed as a spring sheet 4, can be limited.

[0043] In Fig. 5a A clamping device 10 according to the invention is shown. Here, too, a rolling bearing in the form of an angular contact ball bearing 5 is provided between coupling module 1 and screw 2, which has a contact angle BW of 40° (by way of example). In contrast to the one with reference to Fig. 4 In the described embodiment, a disc spring 6a is provided instead of the elastomer ring 6 for sealing and pre-tensioning the hand knob 3. As the Fig. 5a As can be seen, the disc spring 6a is positioned between an underside of the hand knob 3 and an upper side of the collar of the coupling module 11, so that the spring force of the disc spring 6a acts on the underside of the hand knob 3 and the upper side of the collar of the coupling module 11. The disc spring 6a, positioned in this way, serves, among other things, to hold the outer contour of the screw head 12 within a corresponding inner contour of the hand knob 3. Bezugszeichenliste

[0044] 1 Coupling module 2 Screw 3 Hand knob 4 Spring plate 5 Angular contact ball bearing 6 Elastomer ring 6a Disc spring 7 Retaining ring 8 Circlip 9 Stop 10 Clamping device 11 Collar of the coupling module 12 Head of the screw 13 Cylindrical section 14 Thread 16 Inner contour 19 Module contour 20 Drive spindle 22 Internal thread 24 Anti-rotation device 26 Outer contour 30 Flange 100 Hand tool 300 Tool disc 301 Central through opening AR Axial direction BW Contact angle U Circumferential direction

Claims

1. Clamping device (10) for the axial (AR) clamping of a tool disk (300) on a flange (30) associated with a drive spindle (20) of a hand-held power tool (100), wherein the clamping device (10) has a screw (2), which is to be screwed into an internal thread (22) of the drive spindle (20) to securely clamp the tool disk (300), wherein the screw (2) is mounted in a coupling module (1) of the clamping device (10), wherein the coupling module (1) has an internal contour (16) which is paired or can be paired positively with the drive spindle (20) for conjoint rotation in the circumferential direction (UR), characterized in that the clamping device (10) has a disk spring (6a), wherein the disk spring (6a) is designed to seal a grease space between a head (12) of the screw (2) and a collar (11) of the coupling module (1) and / or to axially preload a knob (3), which is designed to be positively locked to the screw (2) for conjoint rotation in the circumferential direction (UR), and in that the screw (2) is mounted in the coupling module (1) by means of a rolling bearing.

2. Clamping device (10) according to Claim 1, characterized in that the clamping device (10) has a clamping member, preferably in the form of a spring plate (4), which can be subjected to an axial clamping force by means of the coupling module (1) in order in this way to clamp the tool disk (300) against the flange (30).

3. Clamping device (10) according to Claim 2, characterized in that the rolling bearing is designed as an angular contact ball bearing (5), wherein the angular contact ball bearing preferably has a contact angle (BW) of between 35 degrees and 45 degrees.

4. Clamping device (10) according to Claim 3, characterized in that the clamping device (10) has a holding ring (7), by means of which the coupling module (1) is held on the screw (2).

5. Clamping device (10) according to either of Claims 3 and 4, characterized in that the clamping member is held on the coupling module (1) by means of a retaining ring (8).

6. Clamping device (10) according to any one of Claims 3 to 5, characterized in that the clamping device (10) has a stop (9), by means of which a deflection of the clamping member is limited directly or indirectly.

7. Hand-held power tool (100), preferably in the form of a cutoff grinder, having a drive spindle (20), which has an internal thread (22) at the end, and having a clamping device according to any one of the preceding claims, wherein the drive spindle (20) has an external contour (26) which is paired positively with the internal contour (16) of the coupling module (1) for conjoint rotation in the circumferential direction (UR).

8. Hand-held power tool (100) according to Claim 7, comprising the flange (30), which is connected or can be connected positively to the drive spindle (20) for conjoint rotation in the circumferential direction (U) by means of an anti-rotation safeguard (24).

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