Hand-held power tool with a disc tool

Abstract

Hand-held power tool, in particular grinding machine and / or polishing machine, with a drive motor (17) for driving a tool holder (23) on which a disc tool (24;25), in particular a grinding disc or polishing disc, can be attached by means of a machine mount (183), and with an eccentric gear (27) which has a drive shaft rotatably coupled to the drive motor (17) and rotatable about a drive axis (36), to or on which a tool shaft (26), on which the tool holder (23) is arranged, is mounted eccentrically to the drive axis (36) by means of a tool shaft bearing (61, 62) for carrying out eccentric movements, wherein the tool shaft (26) performs rotational movements in at least one rotation-eccentric mode when the drive shaft is rotated, in particular due to bearing friction of the tool shaft bearing (61, 62), wherein the tool holder (23) has a rotationally fixed braking surface arrangement (173, 220) for braking the disc tool (24;25) wherein a brake element (170) of the disc tool arranged on a carrier plate (115, 116) rubs against the brake surface arrangement (173, 220), and wherein the disc tool (24; 25) rotates about a rotation axis (36) relative to the rotationally fixed brake surface arrangement (173, 220) during operation of the hand-held machine tool (10), wherein the brake element (170) of the disc tool (24; 25) has at least one spring-loaded step (193) in a pressure direction (195) towards the brake surface arrangement (173, 220), characterized in that the at least one brake element (170) can be detachably fastened to the carrier plate (115, 116) of the disc tool (24; 25) by means of a mounting bracket (204) and the mounting bracket (204) has at least one Ballast weight or counterweight is included.;

Description

[0001] The invention relates to a hand-held power tool, in particular a grinding machine and / or polishing machine, according to the preamble of claim 1. The invention further relates to a disc tool for this purpose.

[0002] Such a hand-held machine tool and such a disc tool are shown in DE 10 2005 062 459 A1.

[0003] DE 100 31 761 A1 describes an eccentric disc sander with a braking agent in the form of an elastic lip.

[0004] US 6,264,539 B1 relates to an eccentric polishing machine with a fixing seat screwed onto the disc tool.

[0005] Eccentric disc sanders, in which the tool holder is mounted eccentrically to the drive axis, are well known, for example from EP 1 491 291 A1. When the drive axis rotates, the bearing friction of the tool shaft bearing, for example, causes the tool shaft and the tool holder mounted on it to move not only eccentrically but also rotationally. If no braking torque acts on the disc tool, usually a round sanding disc, it ultimately rotates at the same speed as the drive shaft. Only when braking occurs, for example, when the tool is placed on the workpiece surface, does the rotational speed of the disc tool decrease. To counteract this, a ring seal is usually arranged on the machine housing of the machine tool, which rubs against the surface, and thus acts as a braking element, of the disc tool.

[0006] A disadvantage of this design is that the seal, which also forms the boundary of a dust extraction area above the disc tool, wears out over time. While the disc tool is usually replaced when worn, the seal is not. This leads to a long-term decline in the quality of the hand-held power tool, as its braking effect diminishes.

[0007] It is therefore the object of the invention to provide improved braking means for hand-held machine tools, in particular grinding machines or polishing machines of the type mentioned above.

[0008] To solve the problem, a hand-held machine tool according to the technical teaching of claim 1 and a plate tool according to the technical teaching of claim 15 are provided.

[0009] A key concept of the invention is that the brake element is replaced immediately when the disc tool wears, so that the braking effect remains essentially constant throughout the entire service life of the hand-held power tool. The brake element of the disc tool has a compliance such that the spring-loaded step ensures that the braking effect in the contact direction remains constant. This compensates for wear of the brake element and / or the braking surface arrangement, and also ensures a uniform braking effect.

[0010] The mounting bracket includes at least one ballast weight or counterweight. The ballast weight or counterweight is, for example, plate-shaped. Furthermore, it is advantageous if the ballast weight or counterweight is ring-shaped or partially ring-shaped. It is understood that several ballast weights or counterweights may be present. Thus, the additional weight has a dual function: firstly, to load or balance the plate tool, and secondly, to hold the brake element in place.

[0011] The step can, for example, be part of a bellows, especially a corrugated bellows. Therefore, the brake element is bellows-like.

[0012] A ring-shaped brake element is particularly preferred. It is understood that segmented brake elements or individual brake element segments joined together to form a ring are also conceivable.

[0013] The design of the step now depends on where the braking effect is desired. As a rule, the step is designed to provide constant braking at the front.

[0014] In this particular embodiment of the invention, the at least one stage is designed as an axial stage or includes an axial stage. This axial stage can, for example, be a circumferential stage if the brake element is ring-shaped. The axial stage is resilient parallel to the axis of rotation. Thus, the friction surface of the brake element is subjected to force in the direction of the axis of rotation, with the axial stage providing compliance.

[0015] The aforementioned circumferential step is expediently a component of an annular recess. This annular recess—like the more generally defined axial step—can extend radially inwards or radially outwards. It is understood that several such steps can be arranged in a row, creating a bellows-like, in particular, pleated bellows-like, structure.

[0016] The at least one step can also include or form a radial step that is resilient transverse to the axis of rotation, for example, at right angles or obliquely. Thus, when braking is applied radially from the outside, the step yields accordingly, but ensures a uniform pressure radially outwards or radially inwards, depending on where the corresponding radial braking surface is located on the machine.

[0017] Several different cross-sections are conceivable for the step. A Z-shaped or V-shaped cross-section is preferred, for example. However, U-shaped cross-sections are also conceivable, and these can be used for both axial and radial steps.

[0018] The brake element advantageously has a mounting recess, particularly annular, for inserting a mounting projection arranged on the support plate. The mounting projection is advantageously formed by or arranged on the aforementioned ballast weight. For example, a radially outer circumferential edge of the ballast weight or counterweight can form the mounting projection, so that the brake element is, so to speak, placed onto the mounting projection, and then the ballast weight or counterweight is attached to the support plate. However, the reverse configuration is also possible, namely, for example, that a plug-in projection is arranged on the brake element, which can be inserted into a plug-in recess in the support plate.

[0019] It is preferred that the plug-in projection of the brake element points radially inwards or – if a mounting recess is provided, which will be explained later in connection with the drawing – that the mounting recess of the brake element is open radially inwards. Thus, the brake element can be slipped over the corresponding plug-in element, for example, over the mounting projection. This approach is particularly advantageous for ring-shaped brake elements, which can be extended radially outwards or pressed radially inwards, but then return to their original shape and essentially pull or push themselves into the mounting projection or plug-in recess on the carrier plate.

[0020] The mounting recess or the plug-in projection on the brake element is advantageously positioned perpendicular to the pressure direction. This prevents forces in the pressure direction from acting on the mounting recess or plug-in projection, particularly when this pressure direction is parallel to the axis of rotation.

[0021] Preferably, the plate tool, for example the aforementioned ballast or counterweight, or another component, for example a base body, has a deformation recess into which the step can deform when subjected to a load opposite to the pressure direction.

[0022] In a particularly preferred embodiment, the brake element is circular. However, it is also possible to use, for example, elliptical or polygonal brake elements. Furthermore, it is conceivable that the brake element is segmented.

[0023] At least one contact surface of the brake surface assembly or the brake element, with which the brake element and the brake surface assembly are in frictional contact, has recesses provided transversely to the pressure direction. These recesses can, for example, serve to cool the brake surface or contact surface. Preferably, the recesses are through-holes. However, it is also possible that the recesses are used to allow a certain amount of "false air" to enter a dust extraction chamber, which is expediently limited by the brake element in conjunction with the brake surface assembly.

[0024] The carrier plate advantageously has, in a manner known per se, an elastically deformable lower part for attaching an abrasive or polishing agent, for example a grinding sheet or a polishing fabric, as well as an upper part comprising the machine mount.

[0025] Channels are expediently provided on the carrier plate, extending from a machining surface facing away from the machine mount to a machine side of the carrier plate that has the machine mount.

[0026] The machine mount and the machine holder should expediently have matching bayonet retaining devices, e.g. bayonet projections and counter-retaining devices.

[0027] The brake element is expediently designed as a seal which, in contact with the brake surface arrangement in conjunction with the tool holder, limits an extraction chamber.

[0028] While a preferred embodiment of the invention is such that the support plate has a round circumferential contour, at least in its working area or on its machining surface, it is understood that the invention can also be applied to support plates with a polygonal circumferential contour.

[0029] Furthermore, it is conceivable that the brake element is attached to the carrier plate eccentrically to the axis of rotation.

[0030] In a preferred embodiment of the invention, the brake element of the plate tool has at least one spring-loaded step in a pressure direction towards the brake surface arrangement.

[0031] Exemplary embodiments of the invention are explained below with reference to the drawing. The drawing shows: Fig. 1 a hand-held machine tool according to the invention shown in perspective obliquely from above with the housing open, Fig. 2 a sectional view of the hand-held machine tool according to Fig. 1 corresponding to a section line AA, Fig. 3 a perspective partial view obliquely from the front of the hand-held machine tool according to Fig. 1. However, with a different tool, Fig. 4 a sectional view accordingly Fig. 8 along a section line BB in Fig. 3, Fig. 5 a perspective oblique view from below of the hand-held machine tool according to Fig. 1 however without tool, which is in the form of a grinding disc in Fig. 6 with a brake element having a brake surface arrangement and in Fig. 7 without the brake element shown from a diagonally above, Fig. 8 a cross-section of the grinding disc according to Fig. 7 along a section line CC in Fig. 7, Fig. 9 the grinding disc according Fig. 6 - 8 from an oblique angle above together with a brake adjusting device which is in Fig. 10 from the top is shown, Fig. 11a the tool according to Fig. 3 from diagonally above, that in Fig. 11b is shown from a diagonal perspective below.

[0032] The drawing shows a hand-held power tool 10, which is configured here as a grinding machine or a polishing machine, depending on the tool used. The hand-held power tool 10 can be operated in an eccentric mode.

[0033] A machine housing 11 of the hand-held power tool 10 comprises a tool area 12 and a motor area 13, which are connected to each other by a handle 14 and a connecting section 15. A drive motor 17, in this case an electric motor, is housed in the motor area 13, although pneumatic motors or other drive principles are also conceivable. The drive motor 17 is supplied with electrical energy via an electrical connection 18. The hand-held power tool 10 is therefore a corded electric machine, although battery operation, and thus a cordless version, is also entirely within the scope of the invention.

[0034] The tool area 12 forms a front face 20 of the machine housing 11. The connecting section 15 runs along a bottom surface 21, and the handle 14 along a top surface 22 of the machine housing 11. A tool holder 23 for holding and receiving tools 24 or 25 (illustrated by way of example) is also arranged on the bottom surface 21. The tool holder 23 is located on the end face of a tool shaft 26.

[0035] The tool holder 23 advantageously has a bayonet 118, although other fastening means, e.g. clamping or screwing means, are also possible.

[0036] An eccentric weight 117 is advantageously arranged on the tool holder 23. The eccentric weight 117 projects downwards from the drive part 33 in the direction of the tool holder 23 as a circular segment.

[0037] The hand-held machine tool 10 is equipped with an eccentric gear 27, which enables eccentric movements of the tool shaft 26 to be generated. The eccentric gear 27 is arranged in the tool area 12 of the machine housing 11.

[0038] A distance between the drive motor 17 and the driven eccentric gear 27 or the tool holder 23, with respect to a longitudinal axis 28 of the machine housing 11, is bridged by a transmission gear 29, which rotaryally couples the drive motor 17 to the eccentric gear 27. The transmission gear 29 has a transmission element 30, which in this case is a transmission belt 31. However, transmission by means of a gear drive or a transmission rod, for example a cardan shaft, would also be conceivable.

[0039] The transmission belt 31 couples an output part 32 of the drive motor 17, arranged on a motor shaft 39 rotating about a motor axis 40, with a drive part 33 of the eccentric gear 27. The drive part 33 rotates about a drive axis 36, to which a tool axis 37 of the tool holder 23 is eccentric by an eccentricity 38, but parallel.

[0040] In this case, the drive axis 36 runs perpendicular to a machining surface 41 of the tool 24 or 25, and thus also perpendicular to a workpiece surface to be machined.

[0041] Inside the handle 14, a control unit 42 is arranged, to which an adjustment element 43 is coupled, for example, an actuator for setting a speed. A motor switch 45 is arranged on a head section 44 of the tool area 12. An operator can reach around the handle 14 through a through-opening 46 provided between the handle 14 and the connecting section 15.

[0042] A dust extraction channel 49 is arranged in the connecting section 15. The dust extraction channel 49 runs within a channel housing 50, which encapsulates the dust extraction channel 49 as far as it extends inside the machine housing 11. This prevents dust-laden air from entering the interior of the machine housing 11. The dust extraction channel 49 runs from the tool holder 23 to an outlet opening 51 on the rear side 19 of the machine housing 11, designed for connecting a suction hose, thus also passing the output section 32. Accordingly, the channel housing 50 has a modified outer contour, also advantageously to provide space for the transmission element 30.

[0043] The drive element 33 is non-rotatably connected to a drive shaft 57. The drive shaft 57 is rotatably mounted about the drive axis 36 on a gearbox housing 60 of the eccentric gearbox 27 by means of drive shaft bearings 58, 59. The gearbox housing 60 is non-rotatably mounted in the machine housing 11. The drive shaft bearings 58, 59 are arranged, for example, in bearing receptacles, in particular steps, of the gearbox housing 60.

[0044] The drive shaft 57 is designed as a hollow shaft that accommodates the tool shaft 26. A central, rod-like section of the tool shaft 26 penetrates a central section of the drive shaft 57, in which the two bearings 58, 59 are also arranged between tool shaft bearings 61, 62. These bearings are mounted on a bearing housing part 63, which is non-rotatably connected to the drive shaft 57, on the side opposite the tool holder 23 and in an interior space of the drive part 33.

[0045] The tool shaft bearings 61, 62 form a tool shaft bearing arrangement. When the drive shaft 57 is driven by the drive element 33, bearing friction in the tool shaft bearings 61, 62 ensures that the tool shaft 26 is also driven along with this rotation about the drive axis 36 and thus performs a rotational movement. If no braking torque acts on the tool shaft 26, the tool shaft 26 rotates at the same speed as the drive shaft 57. Such an operating mode of the eccentric gear 27 is subsequently referred to as free rotation eccentric mode F.

[0046] The tool holder 23 can also be set into forced rotation, in which case it undergoes so-called hypercycloidal movements, i.e., on the one hand a rotation about the drive axis 36, and on the other hand a superimposed eccentric movement caused by the eccentricity 38. This mode is referred to as forced rotation eccentric mode Z, so that the hand-held machine tool with the eccentric modes F and Z has a total of two rotation eccentric modes F, Z.

[0047] For the forced rotation eccentric mode Z, a forced rotation guide 64 is provided, comprising a rolling element 65 and a rolling base 66. At least in the forced rotation eccentric mode Z, the rolling element 65 is rotationally fixed to the tool shaft 26, and the rolling base 66 is rotationally fixed to the gearbox housing 60, and thus also to the machine housing 11. For this purpose, the rolling element 65 and the rolling base 66 are adjusted relative to each other so that they are engaged in the forced rotation mode Z to effect the forced rotation. In the other rotation eccentric mode, namely the free rotation eccentric mode F, the rolling element 65 and the rolling base 66 are separated from each other.

[0048] In this case, the rolling element 65 is designed as a planetary gear arranged inside a ring gear forming the rolling base 66. In forced rotation eccentric mode Z, there is a positive fit between these two components, so that the teeth of the rolling element 65 on its outer circumference mesh with the teeth on the inner circumference of the rolling base 66.

[0049] In addition, an eccentric-only mode N is also possible, in which the tool 24 or 25 does not rotate about the drive axis 36, but merely performs the eccentric movements caused by the eccentricity 38 when the drive motor 17 is running. In this eccentric-only mode N, rotary guide elements 67 engage with the tool shaft 26. The rotary guide elements 67 comprise a first linear guide 68 and a second linear guide 69, which are perpendicular to each other, as well as a guide base 72 that is rotationally fixed with respect to the gearbox housing 60 but axially adjustable in the direction of the drive axis 36. For example, a guide axis q of the first linear guide 68 runs transversely to the longitudinal axis 28, and a guide axis 1 of the second linear guide 69 runs parallel to the longitudinal axis 28.

[0050] The eccentric gear 27 can be switched using a shift handle 84 and a cam gear 88a. The shift handle 84, which acts via a cardan joint 86 on an actuating element 87 rotatable about the drive axis 36, engages and disengages the rotary angle guide means 67 with the tool shaft 26, thus switching into the eccentric-only mode N or out of it into one of the rotational eccentric modes F or Z.

[0051] By rotating the actuating element 87, the cam gear 88a can be rotated to adjust, on the one hand, the position of the rotary angle guide means 67 relative to the tool shaft 26 (switching between modes F and N) and, on the other hand, the relative position of the rolling base 66 to the rolling element 65 (switching between operating modes Z and F). The switching sequence is such that the eccentric gear 27 moves from the forced rotation eccentric mode Z to the free rotation eccentric mode F and from there to the eccentric-only mode N and vice versa (N - F - Z).

[0052] Due to the eccentric-only mode 'N', not only can the tool 24, which has a round carrier plate 115, be used, but also the tool 25, which has a polygonal, in this case triangular, carrier plate 116 (in top view). Thus, the outer contour of the tool 25 is polygonal, which could lead to operator injury, workpiece damage, and other negative consequences in the free-rotation eccentric mode F and the forced-rotation eccentric mode Z. The following measures remedy this: The tool 24 can be attached to the tool holder 23, in particular its bayonet 118, in several relative rotational angle positions.

[0053] The bayonet 118 comprises a bayonet disc 119, which is spring-loaded by means of a spring assembly, e.g., a spring pack 120. A screw 121 penetrates the spring pack 120 and the bayonet disc 119 and is screwed into the tool shaft 26 from below. Thus, the spring pack 120 loads the bayonet disc 119 in the direction of a pressure plate 122. Bayonet projections 123, 124 extend radially outwards from the bayonet disc 119, with bayonet projection 124 being narrower than the other two bayonet projections 123. The projections 123, 124 together form a rotation angle coding 125.

[0054] The bayonet projections 123, 124 can be inserted through bayonet recesses 126, 127 on bayonet receptacles 128 or 129 of the tools 24, 25, whereby the tool 24 or 25 is then rotated relative to the tool receptacle 23, so that the projections 123, 124 come into contact with the interlocking projections 130 of the bayonet receptacles 128, 129 or abut rotation stops 131.

[0055] The bayonet mounts 128 or 129 are machine mounts 183 for attaching the disc tools 24, 25 to the tool holder 23. It is understood that instead of a bayonet connection between the disc tools 24, 25 and the tool holder 23, other fastening methods are also possible, e.g., screws and / or clamping devices, locking devices or the like.

[0056] The bayonet recesses 126 extend over larger rotational angle distances than the narrower bayonet recess 127. Only the narrower bayonet projection 124 fits through the latter. Therefore, it is only possible to attach the rotationally sensitive tool 25, namely the delta plate, to the tool holder 23 if the tool holder 23 and the tool 25 are oriented correctly relative to each other. Thus, the recesses 126 and 127 form a counter-coding 132 that interacts with the rotational angle coding 125.

[0057] For the round tool 24, the spring force of the spring assembly 120, which acts on a contact surface 130b of the tools 24, 25 towards the pressure plate 122, is sufficient to reliably hold the tool 24 on the bayonet 118 even when the drive motor 17 is switched off.

[0058] In contrast, tool 25 is provided with an additional rotary locking mechanism. This rotary locking mechanism comprises a bolt 133, which is expediently operable by a sliding handle 134. In its locked position, where it engages with or behind one of the bayonet projections 123 or 124, the bolt 133 acts as a second rotary stop opposite the rotary stops 131.

[0059] The locking bar 133 is advantageously spring-loaded in the locking position. The operator therefore only needs to actuate the sliding handle 134, i.e., move it towards the machining surface 41 of the tool 25, to move the locking bar 133 into its unlocked position. Locking occurs virtually automatically when the delta tool 25 is rotated into its correct position, namely when its tip 135 points towards the front 20 of the machine housing 11.

[0060] On the side opposite the tip 135, the tool 25 has an actuating projection 140. This projection is suitable, for example, for gripping the tool 25 in order to rotate it. The actuating projection 140 also fulfills a locking function by interacting with a locking element 141. The upper surface of the actuating projection 140, which has a rod-shaped or bar-like form and faces the machine housing 11 in the mounted or to-be-mounted state of the tool 25, forms a locking contour 142 that interacts with the locking element 141. During mounting on the tool holder 23, the locking contour 142 travels a mounting path 143 and finally assumes an end position 144 in the mounted state.Both on the assembly path 143 and in the end position 144, the locking contour 142 interacts with the locking element 141 alternately in such a way that when the tool 25 is in the end position 144, it is not possible to adjust the eccentric gear 27 into one of the rotation-eccentric modes F or Z, or conversely, when the eccentric gear 27 is adjusted into one of these modes, it is not possible to attach the tool 25 to the tool holder 23.

[0061] The carrier plates 115 and 116 could, in principle, be made of a single piece, but in this case, they are constructed in multiple parts. Furthermore, the term "plate" should be understood quite generally, since the carrier plates may also have, for example, bulges or similar features on their upper surface, while their underside is expediently at least essentially flat. For grinding curves or the like, however, it might also be necessary for a grinding plate to have an inward or outward curvature on its respective working surface.

[0062] The carrier plates 115, 116 have a relatively hard, rigid upper part 184, 185, on which the respective machine holder 183 is arranged. The upper part 185 of the tool 25 has the projections and locking contours already described, including the actuating projection 140, which is radial to or protrudes from the bayonet receptacle 129.

[0063] Elastically deformable lower parts 186, 187 are arranged on the underside of the upper parts 184, 185, for example by gluing or by means of a detachable connection, in particular a hook-and-loop fastener. The lower parts 186, 187 are also round or triangular in shape to match the respective outer contours of the carrier plates 115, 116. Carrier plates with other outer contours, e.g., elliptical or polygonal, are also possible.

[0064] Fastening means 180, such as hook and loop fasteners or the like, are arranged on the underside of the lower parts 186, 187 to detachably attach an abrasive or polishing agent.

[0065] It is understood that the carrier plates 115, 166 could also be one piece and / or that they could integrally include an abrasive or polishing agent.

[0066] Extraction openings 181 are arranged on the underside of the carrier plates 115, 116, which communicate via channels 182 leading to the top of the tools 24, 25 with an extraction chamber 117b, which in turn is connected to the dust removal channel 49 when the respective tool 24 or 25 is mounted on the hand-held machine tool 10.

[0067] Seals 149 are arranged on the upper side of the support plates 115, 116, which, in conjunction with the tool holder 23, seal the extraction chamber 117b. However, the seals 149 have an additional function, which will become clear below: In the free-rotation eccentric mode F, a tool attached to the tool holder 23 can, in principle, rotate freely, accelerating up to the speed of the drive shaft 47. Only when the tool experiences a braking torque, for example, when it contacts the workpiece surface being machined, is it decelerated. This can damage the workpiece. The braking devices described in detail below counteract such "autorotation" of the tool attached to the tool holder 23. While they could, in principle, be omitted for the triangular tool 25, they are also useful there to support the rotary angle guides 67. The following description, however, focuses on tool 24.

[0068] The braking means designed according to the invention comprise braking elements 170, which are arranged on the tools 24 or 25 and interact with a braking surface arrangement 173 that is rotationally fixed on the machine side, i.e., rotationally fixed with respect to the tool holder 23. The braking element 170 is formed by the seal 149 or, conversely, the braking element 170 is annular and simultaneously fulfills the function of a seal in connection with dust removal from the machining surface 41.

[0069] The braking surface arrangement 173 comprises a braking element 171b with a braking plate 171, from which a braking segment 172 projects at an angle, for example, at a right angle. An inner surface of the braking segment 172 facing the tool holder 23 forms a radial braking surface 174, while the end face of the braking plate 171 facing the tool 24, 25 provides an end braking surface 175. The braking plate 171 is designed as a ring body.

[0070] Furthermore, the brake element 171b is replaceably or detachably attached to the machine housing 11, for which suitable fastening means, for example clamping devices, screws or – as in the exemplary embodiment – ​​locking devices, may be provided. For example, projections 176 extend radially outwards from the brake element 171b, in particular the brake plate 171, which are designed to engage in corresponding recesses on the machine housing 11. On a side opposite the projections 176, a locking hook 177 is provided on the brake plate 171, which engages with a locking receptacle 178 of the machine housing 11.

[0071] The tool 24 can rotate about a rotation axis, which in this case is the drive axis 36, in free-rotation eccentric mode F. However, a radial braking surface 188 and a face braking surface 189 rub against the radial braking surface 174 and the face braking surface 175 of the braking surface arrangement 173, respectively, so that the rotation of the tool 24 about the rotation axis 36 is braked. The face braking surfaces 175 and 189 are always in frictional contact with each other, thus achieving a constant braking effect. The radial braking surface 174, on the other hand, extends only over a circular segment of a circle around the rotation axis 36, for example, approximately 120°, so that the radial braking surfaces 174 and 188 are only in contact when the tool 24, 25, due to the eccentricity 38, oscillates, so to speak, in the direction of the radial braking surface 174. Thus, the radial braking surface 174 forms, so to speak, a kind of additional brake, which can advantageously be adjustable, as in the embodiment according to Fig. 9, Fig. 10 is the case.

[0072] Furthermore, it would also be possible to replace the brake element 171b with a different brake element whose braking surfaces have a different geometry. For example, a brake element could be provided whose end braking surface has bulges or recesses. Additionally, the geometric extent of the brake segment 172 could be different, so that, for example, a brake segment extending over a larger or smaller angular section is provided, or a brake segment whose inner curvature does not correspond to the radius of the brake element 170 on its outer side.

[0073] It should also be noted at this point that it is an expedient, but not mandatory, embodiment of the invention that the radii of brake segment 172 and brake element 170 correspond in the area of ​​their contact surfaces, but that different radii of curvature are also possible.

[0074] The brake surface arrangement 173 advantageously exhibits less wear and thus higher abrasion resistance than the brake element 170. The brake element 170 is now an integral part of the tool 24 or 25. When the entire tool wears out, for example because the lower parts 186, 187 are worn, the brake element 170 also needs to be replaced. Thus, a substantially constant braking effect can be achieved over the entire operating life of the respective tool 24 or 25.

[0075] This very uniform braking effect is also due to the fact that the brake element 170 is flexible both radially and axially with respect to the axis of rotation 36.

[0076] The brake element 170 is in the present case annular, but other brake elements, e.g. elliptical, are also conceivable.

[0077] Furthermore, the brake element 170 is centric to the machine mount 183, although an eccentric arrangement is also conceivable.

[0078] The brake element 170 comprises a brake ring section 190, which provides the radial braking surface 188 and the end braking surface 189. Thus, the brake ring section 190 is a kind of bead that forms a free end of the brake element 170 axially (with respect to the axis of rotation 36). The end braking surface 189 also features circular segment-shaped brake projections 191, between which recesses 192 are arranged. The brake projections 191 essentially form brake shoes that can wear down gradually until the base of the brake ring section 190 is reached. The recesses 192 provide circumferential openings through which cooling air can flow into the friction area between the brake element 170 and the brake surface arrangement 173, thus preventing overheating.

[0079] The radial outer circumference of the brake ring section 190 is designed for braking contact with the radial braking surface 174. The radial braking surface 188 has an inclined position relative to the drive axis 36 and relative to the associated radial braking surface 174. Thus, the radial braking surface 188 is designed as a kind of circumferential projection which, with corresponding abrasion and wear, becomes wider in relation to the contact with the rotationally fixed radial braking surface 174.

[0080] The brake element 170, due to the flexible material from which it is made, for example, a correspondingly soft plastic or rubber material, has a certain degree of compliance, thus enabling a self-adjusting effect or a uniform braking effect. Furthermore, flexibility is achieved through a step 193. The step 193 is an axial step, meaning it is flexible parallel to the axis of rotation 36. This ensures that the end brake surface 189 is always pressed in the direction of the rotationally fixed end brake surface 175, thus maintaining frictional contact.

[0081] Step 193 is a circumferential step. It forms part of an annular recess 194. Step 193 has a V-shaped cross-section. Step 193 is, so to speak, a horizontal step (in cross-section with respect to the axis of rotation 36) such that it is resiliently compliant against a pressure direction 195 (parallel to the axis of rotation 36). Fig. Figure 8 is a schematically indicated spring-loaded position 196.

[0082] Particularly in the compressed position 196, the brake element 170 can deform into a deformation recess 197 on the upper side of the tool 25. This measure is optional.

[0083] It is understood that differently designed steps, e.g. a Z-shaped axial step 198 or a Z-shaped radial step 199, may also be provided (in Fig. 8 schematically indicated). The radial step 199 is radially flexible to the axis of rotation 36 in order to improve the contact with the radial braking surface 174.

[0084] It is understood that, for interaction with the tool 24, i.e. with a ring-shaped, stepped brake element according to the invention, a circumferentially closed radial brake surface (not shown) could also be provided instead of the circular segment radial brake surface.

[0085] The step 193 comprises an inclined section 200 extending obliquely downwards to the axis of rotation 36, i.e., towards the machine mount 183 and the top of the tool 24, which forms one leg of the V-shaped step 193. A short bottom section 201, with respect to the axis of rotation 36, adjoins the inclined section 200. Opposite the inclined section 200 lies a contact leg 202 of the step 193.

[0086] The step 193 is followed by a radially inwardly open mounting recess 203, which serves to mount the brake element 170 to the upper part 184. The mounting recess 203 is an annular groove into which individual locking hooks engage in the case of the upper part 185, while in the case of the upper part 184, a mounting bracket 204 engages. The mounting bracket 204 comprises an annular plate that serves as a ballast weight or counterweight. Thus, the weight ratios of both tools 24 and 25 are similar or the same.

[0087] The mounting bracket 204 comprises an annular plate with a central through-opening 205 for a ring body 206 of the bayonet mount 128. The rear gripping projections 130 extend radially inwards from the ring body 206.

[0088] Furthermore, the mounting bracket 204 has through-openings 207 that fit the channels 182, allowing dust-laden air from below to pass through the annular space bounded by the seal 159. The mounting bracket 204 could, for example, be attached to the carrier plate 115 by means of a clamping or snap-fit ​​connection, but in this case it is screwed on by means of screws 208.

[0089] The brake element 170 is, by means of its mounting recess 203, essentially slipped over the radially outer edge or circumferential edge of the mounting bracket 204, so that the circumferential edge engages in the mounting recess 203. This alone ensures a secure hold of the brake element 170 on the mounting bracket 204. In addition, the brake element 170 is pressed against the upper part 184 by means of a leg 209, facing the upper part 184 and shown as the lower leg in the drawing, which comes to rest between the mounting bracket 204 and the upper part 184. A ring-shaped recess is advantageously provided on the upper part 184 for the leg 209, although this is not strictly necessary.

[0090] Instead of the fixed, non-adjustable brake surface arrangement 173, the arrangement shown in the Fig. 9 and Fig. The brake surface arrangement 220 shown in 10 can be used.

[0091] The brake surface arrangement 220 according to this embodiment comprises a brake body 221, with a brake segment 222, the end face of which facing the brake member 170 comprises a radial brake surface 224.

[0092] A retaining projection 223 extends from the brake segment 222, which only covers a partial circumference of a circle around the axis of rotation 36. A brake segment 222 of a brake adjusting device 225 is screwed into this projection. The adjusting element 226 includes a screw that can be adjusted or screwed in by means of a handle 227. The adjusting element 226 is screwed into and penetrates a holder 228. Thus, by turning the handle 227, the axial position of the adjusting element 226 can be adjusted radially to the axis of rotation 36, whereby the brake body 221 is moved along an adjustment path 229 towards or away from the brake member 170. This allows the braking effect of the radial braking surface 224 to be changed, preferably even completely eliminated, if the brake body 221 is moved radially farther away from the brake member 170.The brake adjusting device 225 with the brake body 221 could, for example, be arranged on the machine housing 11 instead of the brake segment 172.

[0093] During its rotation around the drive axis 36, the tool 25, and consequently also the brake element 170, oscillates eccentrically due to the eccentricity 38. This results in, among other things, a braking position further away from the radial braking surface 224 (indicated by dashed lines) and a braking position (shown by solid lines) where it is in braking contact or frictional contact with the brake body 221. Therefore, when the brake body 221 is moved further away from the axis of rotation 36 along the adjustment path 229, this phase of frictional and braking engagement is shorter, thus reducing the braking effect. However, when moved towards the axis of rotation 36, the braking effect of the brake body 221 is greater.

[0094] It is understood that the braking effect could also be altered by other measures, e.g., by changing the effective contact area of ​​the radial braking surface 224, which can be achieved, for example, by changing its radius of curvature. Thus, if the circumferential end regions of the brake segment 222 are, for example, fixed in position, the central section of the brake segment 222 could be adjusted by moving the adjusting element 226 along the adjustment path 229, thereby also changing the curvature of the radial braking surface 224.

Claims

[1] Hand-held power tool, in particular grinding machine and / or polishing machine, with a drive motor (17) for driving a tool holder (23) on which a disc tool (24;25), in particular a grinding disc or polishing disc, can be attached by means of a machine mount (183), and with an eccentric gear (27) which has a drive shaft rotatably coupled to the drive motor (17) and rotatable about a drive axis (36), to or on which a tool shaft (26), on which the tool holder (23) is arranged, is mounted eccentrically to the drive axis (36) by means of a tool shaft bearing (61, 62) for carrying out eccentric movements, wherein the tool shaft (26) performs rotational movements in at least one rotation-eccentric mode when the drive shaft is rotated, in particular due to bearing friction of the tool shaft bearing (61, 62), wherein the tool holder (23) has a rotationally fixed braking surface arrangement (173, 220) for braking the disc tool (24;25) having a brake element (170) of the disc tool arranged on a carrier plate (115, 116) rubs against the brake surface arrangement (173, 220), and having the disc tool (24; 25) rotating about a rotation axis (36) relative to the rotationally fixed brake surface arrangement (173, 220) when the hand-held machine tool (10) is operated, wherein the brake element (170) of the disc tool (24; 25) has at least one step (193) that is resilient in a pressure direction (195) towards the brake surface arrangement (173, 220), ; characterized by , that the at least one brake element (170) can be detachably attached to the carrier plate (115, 116) of the plate tool (24; 25) by means of a mounting bracket (204) and the mounting bracket (204) includes at least one ballast weight or counterweight. [2] Hand-held machine tool according to claim 1, characterized by , that the brake element (170) is ring-shaped. [3] Hand-held machine tool according to claim 1 or 2, characterized by, that the at least one step (193) comprises an axial step (198) designed in particular as a circumferential step, which is resilient parallel to the axis of rotation (36). [4] Hand-held machine tool according to claim 3, characterized by , that the circumferential step is a component of a ring recess (194). [5] Hand-held machine tool according to one of the preceding claims, characterized by , that the at least one step (193) comprises a radial step (199) which is resilient transverse, in particular perpendicular, to the axis of rotation (36). [6] Hand-held machine tool according to one of the preceding claims, characterized by , that at least one step (193) has a z-shaped, v-shaped or U-shaped cross-section. [7] Hand-held machine tool according to one of the preceding claims, characterized by that at least one ballast weight or counterweight is partially ring-shaped or ring-shaped. [8] Hand-held machine tool according to one of the preceding claims, characterized by , that the brake element (170) comprises a mounting recess (203) in particular annular shape for inserting a mounting projection arranged on the carrier plate (115, 116) or a plug-in projection in particular annular shape for insertion into a plug-in recess arranged on the carrier plate (115, 116). [9] Hand-held machine tool according to claim 8, characterized by , that the mounting recess (203) or the plug-in projection runs transversely to the pressure direction (195). [10] Hand-held machine tool according to any of the preceding claims, characterized by , that the plate tool (24; 25) has at least one deformation recess (197) into which the at least one step (193) can be deformed when subjected to a load opposite to the pressure direction (195). [11] Hand-held machine tool according to any of the preceding claims, characterized by, that the brake element (170) is annular or elliptical and / or segmented. [12] Hand-held machine tool according to any of the preceding claims, characterized by , that recesses (192) are arranged transversely to the pressure direction (195) on at least one contact surface of the brake surface arrangement (173, 220) and / or the brake element (170), with which the brake surface arrangement (173, 220) is in frictional contact with the brake element (170) or vice versa. [13] Hand-held machine tool according to one of the preceding claims, characterized bythat the carrier plate (115, 116) has an elastically deformable lower part (186, 187) for attaching an abrasive or polishing agent and an upper part (184, 185) having the machine holder (183) and / or that the carrier plate (115, 116) has channels (182) extending from a machining surface (41) facing away from the machine holder (183) to a machine side of the carrier plate (115, 116) having the machine holder (183) and / or that the tool holder (23) (24; 25) and the machine holder (183) have bayonet retaining means (128, 129) that fit together and / or that the brake element (170) is designed as a seal (149) which, upon contact with the brake surface arrangement (173, 220) in conjunction with the tool holder (23) a suction chamber (117b) is defined and / or that the support plate (115, 116) has a round or polygonal perimeter contour. [14] Hand-held machine tool according to one of the preceding claims, characterized by , that the brake element (170) is attached eccentrically to the axis of rotation (36) on the carrier plate (115, 116). [15] Disc tool (24; 25), in particular grinding disc or polishing disc, for a hand-held power tool (10), in particular grinding machine and / or polishing machine, wherein the hand-held power tool (10) has a drive motor (17) for driving a tool holder (23) on which the disc tool (24;25) can be attached by means of a machine mount (183), wherein the hand-held machine tool (10) has an eccentric drive (27) which has a drive shaft rotatably coupled to the drive motor (17) and rotatable about a drive axis (36), to or on which a tool shaft (26), on which the tool holder (23) is arranged, is mounted eccentrically to the drive axis (36) by means of a tool shaft bearing (61, 62) for carrying out eccentric movements, wherein the tool shaft (26) performs rotational movements in at least one rotation-eccentric mode when the drive shaft rotates, in particular due to bearing friction of the tool shaft bearing (61, 62), wherein the tool holder (23) has a rotationally fixed braking surface arrangement (173, 220) for braking the disc tool (24; 25), wherein the disc tool (24;25) has a brake element (170) arranged on a carrier plate (115, 116) for rubbing against the brake surface arrangement (173, 220) and rotates about an axis of rotation (36) relative to the rotationally fixed brake surface arrangement (173, 220) when the hand-held machine tool (10) is operated, wherein the brake element (170) of the disc tool (24; 25) has at least one step (193) that is resilient in a pressure direction (195) towards the brake surface arrangement (173, 220), ; characterized by , that the at least one brake element (170) can be detachably attached to the carrier plate (115, 116) of the plate tool (24; 25) by means of a mounting bracket (204) and the mounting bracket (204) includes at least one ballast weight or counterweight.

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