EP2366492B1 - Manually operated machine tool with a radial brake - Google Patents

Abstract

The tool has a drive motor for driving a tool holder (23), and an eccentric gear comprising a drive shaft. A disk tool (24) e.g. grinding disk, is fastened to the motor by a machine holder. A tool shaft (26) executes rotational movements in a rotation-eccentric mode during rotation of the drive shaft. A brake surface arrangement (173) for braking the disk tool is arranged in the tool holder. The disk tool is rotated around a drive axis (36) relative to the arrangement, where the arrangement has a radial braking surface that extends over a circle segment of a circle around the axis.

Description

The invention relates to a hand-held machine tool, in particular a grinding machine and / or polishing machine, according to the preamble of claim 1.

Such a hand-held machine tool goes out US 5813903 A out.

Eccentric disc grinder, in which the tool holder is mounted eccentrically to the drive axle, are well known, such. B. off EP 1 4 91 2 91 A1 , When the drive shaft rotates, for example, the bearing friction of the tool shaft bearing causes the tool shaft and the tool holder arranged thereon to make not only an eccentric movement, but also a rotational movement. If no braking torque acts on the plate tool, usually a round grinding plate, this ultimately rotates at the same speed as the drive shaft. Only when a braking begins, for example by the tool is placed on the workpiece surface to be machined, the speed of the plate tool decreases. To remedy this, a ring seal is usually arranged on the machine housing of the machine tool, which rubs on the surface, thus a braking member of the plate tool.

A disadvantage of this construction is that the surface of the plate tool, so therefore the brake member is permanently in contact with the brake surface assembly, which is usually of a seal is provided. This can lead to unwanted heating during operation. The braking effect also depends on the extent of the end faces of the brake member and the braking surface arrangement, with which the two components rub against each other.

It is therefore the object of the invention to provide improved braking means in manual machine tools, in particular grinding machines or polishing machines of the type mentioned.

To solve the problem, a hand-held power tool according to claim 1 is provided.

A basic idea of the invention is that the radial brake surface acts from radially outside or inside on the brake member on the plate tool. As a result, the eccentricity of the tool holder is used with respect to the axis of rotation. Thus, therefore, in a preferred embodiment of the invention, the radial braking surface and the braking member due to the eccentricity of the tool holder to the rotation axis only be in frictional engagement with each other over a partial revolution of the plate tool. Thus, the radial braking surface, which comprises only one circular segment, does not brake constantly, but only partially. One could therefore call the radial brake surface as a radial segment brake surface.

The tool holder thus has insofar a rotationally fixed brake surface arrangement for braking the plate tool, as the brake surface arrangement is arranged in the tool holder or in the region of the tool holder. The rotating brake member of the plate tool can therefore be braked by the rotationally fixed relative to the machine housing brake surface arrangement.

The braking surface arrangement may be formed by the machine housing of the hand-held machine tool or may be non-rotatably connected or connectable thereto with respect to the tool holder.

The brake member is expediently arranged on the plate tool or preferably formed by the plate tool. For example, the braking member is formed by a support plate of the plate tool. It is advantageous that the brake member is arranged on a support plate of the plate tool.

The tool shaft can be very short. Preferably, a brake adjustment device is provided, with which the braking effect of the radial braking surface is adjustable. The brake adjusting device can, for example, adjust the radial braking surface along an adjustment path transversely to the axis of rotation, ie toward or away from the braking member.

Furthermore, it is possible that the brake adjusting device adjusts a curvature of the radial braking surface. If the radial braking surface deflected stronger, for example, larger surface portions thereof may be in frictional engagement with the brake member. However, if the radial braking surface is more curved, for example, their respective longitudinal end portions (in the circumferential direction) may be in contact with the braking member.

Another aspect provides that the brake adjustment device changes a circumferential length of the radial brake surface, so that it is thus configured to adjust a circumferential length of the radial brake surface. For example, telescopic elements would be conceivable here. Furthermore, it is possible that the radial braking surface is segmented, so that individual segments are adjustable towards or away from the axis of rotation so as to enlarge or reduce the radial braking surface in segments.

It is preferred if the radial brake surface can be completely disengaged from the brake member. The displacement of the brake adjustment is then preferably designed so that the radial braking surface is sufficient in a region outside the range of the brake member in a rotation about the axis of rotation including the eccentricity.

The radial braking surface is spring-loaded in a preferred embodiment of the invention to the brake member. Alternatively or in addition to this would also be a spring-elastic brake body possible. Thus, so the radial brake rebounds, so that it always produces the frictional engagement with the brake member.

It is understood that the radial braking surface is indeed arranged in a preferred, easily realizable embodiment radially outward relative to the brake member. However, it is also possible to arrange the radial braking surface radially inwards or also to provide radially inward and radially outward inventive radial braking surfaces.

According to the invention, it is provided that the braking surface arrangement has at least one end braking surface running transversely, in particular perpendicularly, to the axis of rotation.

Just this face brake surface is suitable for producing a constant braking effect by always in frictional contact with the brake member.

A further embodiment provides that the braking surface arrangement is arranged on a brake element, which is arranged on the basis of fastening means releasably on a machine housing of the hand-held machine tool. The fastening means comprise, for example, latching means and / or clamping means and / or screws. The replaceable brake element makes it possible, for example, to install different radial brake surfaces depending on the desired braking effect. For example, a brake element with a smaller radial braking surface can be exchanged for another braking element with a larger radial braking surface.

In a preferred embodiment of the invention, the brake member of the plate tool at least one in a direction of pressure to the brake surface assembly towards resilient step.

The braking surface arrangement, in particular the radial braking surface, may be resiliently yielding to the braking member due to at least one stage. Thus, so the radial brake rebounds, so that it always produces the frictional engagement with the brake member of the tool. The following remarks and the embodiments in connection with the drawing for the embodiment of the stage can therefore also be used in the machine-side braking surface arrangement, in particular in the case of the radial braking surface.

The stage may for example be part of a bellows, in particular a bellows. Thus, the brake member is thus bellows.

The configuration of the stage now depends on where the braking effect is desired. In general, the stage is designed so that a front-side constant braking is desired.

In particular, in this embodiment, the at least one stage is designed as an axial stage or comprises an axial stage. This axial stage may be, for example, a circumferential step when the brake member is annular. The axial stage is resilient parallel to the axis of rotation. Thus, therefore, the friction surface of the brake member is subjected to force in the direction of the axis of rotation, wherein by the axial step a compliance is present.

The aforementioned circumferential step is expediently a component of an annular recess. This annular recess can - as well as the somewhat more general formulated axial stage - run radially inward or radially outward. It is understood that several such stages can be strung together, so that a bellows-like, especially bellows-like, structure arises.

However, the at least one step may also include or form a radial step, which is transversely, for example perpendicularly transversely or obliquely, resilient to the axis of rotation. Thus, if braked by radially outward, the step correspondingly, but ensures a uniform pressure radially outward or radially inward, depending on where the corresponding radial braking surface is arranged on the machine.

Regarding the stage several different cross sections are conceivable. For example, a Z-shaped or V-shaped cross section is preferred. But also U-shaped cross-sections are conceivable, and these can be used both in the axial stage and in the radial stage application.

The brake member may form an integral part of the carrier plate. For example, it may be formed directly in an injection molding process to the support plate. Preferably, however, the brake member is releasably secured to the support plate, for example by means of appropriate fastening means, preferably screws, plug-in supports and / or plug-in projections, clamping brackets or the like.

The brake member on the tool or the brake surface assembly is indeed circular in a particularly preferred embodiment. But it is also possible that, for example, elliptical or polygonal brake links or braking surface arrangements provides. Furthermore, it is conceivable that the braking member or the braking surface arrangement is segmented.

At least one contact surface of the braking surface arrangement or of the braking member with which the braking member and the braking surface arrangement are in frictional contact, recesses are provided transversely to the pressing direction. These recesses can serve, for example, to the braking surface or contact surface cool. Preferably, the recesses are passages. But it is also possible that the recesses are used to ensure that a certain proportion of "false air" enters a dust-suction, which is limited by the brake member expediently in cooperation with the brake surface assembly.

The support plate has in a conventional manner expediently an elastically deformable lower part for attachment of an abrasive or polishing agent, such as an abrasive sheet or a Poliergewirks, as well as the machine holder exhibiting upper part.

Channels are expediently provided on the carrier plate, which extend from a processing surface facing away from the machine holder to a machine side of the carrier plate having the machine holder.

The machine mount and the machine mount suitably have mating bayonet means, e.g. Bayonet projections and counter-holdings.

The brake member is expediently designed as a seal which limits a suction space in contact with the braking surface arrangement in cooperation with the tool holder.

Although a preferred embodiment of the invention is such that the support plate, at least in its working area or on its working surface, has a round peripheral contour. It is understood that the invention can also be applied to carrier plates with a polygonal peripheral contour.

Furthermore, it is conceivable that the brake member is mounted eccentrically to the axis of rotation on the support plate.

Figur 1

eine erfindungsgemäße Hand-Werkzeugmaschine perspektivisch schräg von oben mit geöffnetem Gehäuse,

Figur 2

eine Schnittdarstellung der Hand-Werkzeugmaschine gemäß Figur 1 entsprechend einer Schnittlinie A-A,

Figur 3

eine perspektivische Teilansicht schräg von vorn der Hand-Werkzeugmaschine gemäß Figur 1 jedoch mit einem anderen Werkzeug,

Figur 4

eine Schnittansicht entsprechend Figur 8 entlang einer Schnittlinie B-B in Figur 3,

Figur 5

eine perspektivische Schrägansicht von unten der Hand-Werkzeugmaschine gemäß Figur 1 jedoch ohne Werkzeug, das in Gestalt eines Schleiftellers in

Figur 6

mit einem eine Bremsflächenanordnung aufweisenden Bremselement und in

Figur 7

ohne das Bremselement von schräg oben dargestellt ist,

Figur 8

einen Querschnitt des Schleiftellers gemäß Figur 7 entlang einer Schnittlinie C-C in Figur 7,

Figur 9

den Schleifteller gemäß Figuren 6 - 8 von schräg oben zusammen mit einer Bremseinstelleinrichtung, die in

Figur 10

von oben dargestellt ist,

Figur 11a

das Werkzeug gemäß Figur 3 von schräg oben, das in

Figur 11b

von schräg unten dargestellt ist.

Hereinafter, embodiments of the invention will be explained with reference to the drawing. Show it:

FIG. 1

a hand-held machine tool according to the invention obliquely from above with the housing open,

FIG. 2

a sectional view of the hand-held machine tool according to FIG. 1 according to a section line AA,

FIG. 3

a partial perspective view obliquely from the front of the hand-held machine tool according to FIG. 1 however with another tool,

FIG. 4

a sectional view accordingly FIG. 8 along a section line BB in FIG. 3 .

FIG. 5

an oblique perspective view from below of the hand-held machine tool according to FIG. 1 However, without tools, in the form of a sanding plate in

FIG. 6

with a braking surface arrangement having a braking element and in

FIG. 7

without the brake element being shown obliquely from above,

FIG. 8

a cross section of the sanding pad according to FIG. 7 along a section line CC in FIG. 7 .

FIG. 9

according to the sanding pad FIGS. 6-8 obliquely from above together with a brake adjusting device, which in

FIG. 10

is shown from above,

FIG. 11a

the tool according to FIG. 3 from diagonally above, that in

FIG. 11b

is shown obliquely from below.

The drawing shows a hand machine tool 10, which in the present case is designed as a grinding machine or polishing machine, depending on which tool is used. The hand machine tool 10 can be operated in an eccentric mode.

A machine housing 11 of the hand-held machine tool 10 comprises a tool area 12 and a motor area 13, which are connected to one another by a handle 14 and a connecting section 15. In the motor region 13, a drive motor 17 is housed, in this case an electric motor, wherein 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 wired electrical machine, whereby a battery operation, thus a wireless variant is well within the scope of the invention.

The tool portion 12 forms a front side 20 of the machine housing 11. The connecting portion 15 extends on a bottom 21, the handle 14 on an upper side 22 of the machine housing 11. On the bottom 21 is also a tool holder 23 for holding and receiving exemplified tools 24 or 25 arranged. The tool holder 23 is arranged on the front side of a tool shaft 26.

The tool holder 23 advantageously has a bayonet 118, wherein other fastening means, such as clamping or screw means are possible.

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

In the hand-held power tool 10, an eccentric 27 is provided, with the eccentric movements of the tool shaft 26 can be generated. The eccentric 27 is disposed in the tool area 12 of the machine housing 11.

A distance between the drive motor 17 and the driven eccentric 27 and the tool holder 23 with respect to a longitudinal axis 28 of the machine housing 11 is bridged by a transmission gear 29 which rotatably couples the drive motor 17 with the eccentric 27. The transmission gear 29 has a transmission member 30 in which it is present and a transmission belt 31. Conceivable, however, would be a transmission by means of a toothed gear or a transmission rod, for example, a propeller shaft.

The transmission belt 31 couples a driven part 32 of the drive motor 17 arranged on a motor shaft 39 rotating about a motor shaft 40 to a drive part 33 of the eccentric drive 27. The drive part 33 rotates about a drive axis 36 to which a tool axis 37 of the tool holder 23 eccentrically around an eccentricity 38 but is parallel.

In the present case, the drive axle 36 runs perpendicular to a machining surface 41 of the tool 24 or 25, and therefore also perpendicular to a workpiece surface to be machined.

In the interior of the handle 14, a controller 42 is arranged, to which an adjusting element 43 is coupled, for example a Control element for setting a speed. At a head portion 44 of the tool area 12, a motor switch 45 is arranged. An operator can grip around the handle 14 through a penetration opening 46 provided between the handle 14 and the connection portion 15.

In the connecting portion 15, a dust discharge channel 49 is arranged. The dust removal channel 49 extends in a channel housing 50, which encapsulates the dust removal channel 49, as far as it runs in the interior of the machine housing 11. Thus dust-laden air does not enter the interior of the machine housing 11. The dust removal channel 49 extends from the tool holder 23 to a configured for connection of a suction hose discharge port 51 on the rear side 19 of the machine housing 11, that is also on the output member 32 over. The channel housing 50 accordingly has an adapted outer contour, expediently also to provide movement space for the transmission member 30.

The drive member 33 is rotatably connected to a drive shaft 57. The drive shaft 57 is mounted by means of drive shaft bearings 58, 59 rotatably about the drive shaft 36 to a transmission housing 60 of the eccentric 27. The gear housing 60 is rotatably received in the machine housing 11. The drive shaft bearings 58, 59 are arranged, for example, in bearing receivers, in particular stages, of the transmission housing 60.

The drive shaft 57 is configured here as a hollow shaft which receives the tool shaft 26. A middle, rod-like portion of the tool shaft 26 penetrates a central portion of the drive shaft 57, in which the two bearings 58, 59 between tool shaft bearings 61, 62 arranged on a rotatably connected to the drive shaft 57 bearing receiving part 63 on the tool holder 23 opposite side and in an interior of the drive member 33rd

The tool shaft bearings 61, 62 form a tool shaft bearing. If the drive shaft 57 is now driven by the drive part 33, a bearing friction of the tool shaft bearings 61, 62 ensures that the tool shaft 26 is also taken to this rotation about the drive axis 36 and thus performs a rotational movement. When 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 operation mode of the eccentric gear 27 is hereinafter referred to as a free rotation eccentric mode F.

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

For the forced rotation eccentric mode Z, a forcible rotation guide 64 is provided which includes a rolling element 65 and a rolling base 66. At least in the forced rotation eccentric mode Z of the rolling elements 65 with the tool shaft 26 is rotationally fixed and the rolling base 66 with the gear housing 60 rotatably, thus also the machine housing 11, rotatably. For this purpose, the rolling element 65 and the rolling base 66 are adjusted relative to each other so that they are in the forced rotation eccentric Z in engagement 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. In the present case, the rolling element 65 is configured as a planetary gear, which is arranged in the interior of a rolling gear 66 forming the ring gear. In the forced rotation eccentric mode Z, there is a form fit between these two components, so that the rolling element 65 with its toothing on the outer circumference meshes with the toothing on the inner circumference of the rolling base 66.

In addition, however, an only eccentric mode N is possible in which the tool 24 or 25 does not rotate about the drive shaft 36, but only performs the eccentric movements caused by the eccentric 38 when the drive motor 17 is running. In this eccentric cam mode N, rotational angle guide means 67 are engaged with the tool shaft 26. The rotation angle guide means 67 comprise a first linear guide 68, and a second linear guide 69, which are mutually perpendicular, and with respect to the gear housing 60 non-rotatable, but in the direction of the drive shaft 36 axially adjustable guide base 72. A guide axis q of the first linear guide 68 extends, for example transverse to the longitudinal axis 28, a guide axis 1 of the second linear guide 69 parallel to the longitudinal axis 28th

The eccentric 27 is switchable with a handle 84 and a sliding gear 88a. By means of the switching handle 84, which acts via a universal joint 86 on a rotatable about the drive shaft 36 actuator 87, the rotation angle guide means 67 are engaged and disengaged to bring the tool shaft 26 so as to switch to the eccentric only mode N or out of it into one of the rotation eccentric modes F or Z.

By a rotary actuation of the actuator 87 can be turn gear 88a drehverstellen to one hand, the position of the rotation angle guide means 67 relative to the tool shaft 26 to adjust (switching between the modes F and N) and on the other the relative position of the rolling base 66 to the rolling element 65 (switching between the operating modes Z and F). In this case, the switching sequence is such that the eccentric 27 passes from the forced rotation eccentric Z mode in the free rotation eccentric mode F and from there into the only eccentric mode N and vice versa (N - F - Z).

• Das Werkzeug 24 kann in mehreren Relativ-Drehwinkelstellungen an der Werkzeugaufnahme 23, insbesondere deren Bajonett 118, befestigt werden.

Due to the eccentric only mode 'N, not only the tool 24 having a circular support plate 115 can be used, but also the tool 25 having a polygonal, presently triangular support plate 116 (in plan view). Thus, therefore, the outer contour of the tool 25 is polygonal, which could lead to injury to the operator, damage to the workpiece and the like other negative consequences in the free rotation eccentric mode F and the forced rotation eccentric mode Z. Here are the following measures to remedy the situation:

• The tool 24 can be attached to the tool holder 23, in particular its bayonet 118, in a plurality of relative angular positions.

The bayonet 118 comprises a bayonet disc 119, which by means of a spring arrangement, for. B. a spring assembly 120, is spring loaded. A screw 121 penetrates the spring assembly 120 and the bayonet disc 119 and is screwed from below into the tool shaft 26. Thus, the spring assembly 120 loads the bayonet plate 119 in the direction of a pressure plate 122. From the bayonet disc 119 are bayonet projections 123, 124 radially outwardly from, wherein the bayonet projection 124 is narrower than the other two bayonet projections 123. The projections 123, 124 together form a rotation angle coding 125.

The bayonet projections 123, 124 can through bayonet recesses 126, 127 on bayonet receptacles 128 or 129 of the Tools 24, 25 are pushed through, in which case the tool 24 or 25 is rotated relative to the tool holder 23, so that the projections 123, 124 with Hintergreifvorsprüngen 130 of the bayonet receptacles 128, 129 come to rest or strike against rotational stops 131.

The bayonet receptacles 128 or 129 are machine mounts 183 for attaching the plate tools 24, 25 to the tool holder 23. It is understood that instead of a bayonet connection between the plate tools 24, 25 on the tool holder 23 also other types of fastening in Come question, eg Screw means and / or clamping means, latching means or the like.

The bayonet recesses 126 extend over larger rotational angular distances than the narrower bayonet recess 127. Only the narrower bayonet projection 124 passes through them. Thus, it is only possible that rotation-angle-sensitive tool 25, namely the delta plate to attach to the tool holder 23 when the tool holder 23 and the tool 25 are rotationally correct to each other. Thus, therefore, the recesses 126, 127 form a counter-coding 132, which cooperates with the rotation angle coding 125.

In the case of the round tool 24, the spring force of the spring assembly 120, which applies a contact surface 130b of the tools 24, 25 to 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.

The tool 25, however, an additional twist lock is provided. The rotation lock comprises a latch 133, which is expediently actuated by a push handle 134. The latch 133 acts in its locking position, in the he engages in one of the bayonet projections 123 or 124 or engages behind this, as the second, the rotation stops 131 opposite rotational stop.

The latch 133 is advantageously spring-loaded in the locking position. Thus, the operator only has to operate the push handle 134, i. in the direction of the working surface 41 of the tool 25 to adjust the latch 133 in its release position. The locking occurs almost automatically when the delta tool 25 is rotated to its correct position, namely, when its tip 135 faces the front 20 of the machine housing 11.

At the opposite side of the tip 135, the tool 25 has an actuating projection 140. This is suitable, for example, for gripping the tool 25 in order to rotate it. In addition, the actuating projection 140 also fulfills a blocking function in which it interacts with a blocking body 141. A machine housing 11 in the assembled state or to be mounted state of the tool 25 facing upper side of the actuating projection 140, which has a rod-shaped or rod-shaped configuration, forms a locking contour 142 which cooperates with the locking body 141. The locking contour 142 passes through a mounting path 143 when mounted on the tool holder 23 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 cooperates with the locking body 141 and that alternately such that when located in the end position 144 tool 25, an adjustment of the eccentric 27 in one of the rotation eccentric modes F or Z not possible is and vice versa, when the eccentric 27 is adjusted in one of these modes, it is not possible to attach the tool 25 to the tool holder 23.

Although the support plates 115, 116 could be in one piece in principle, but in the present case are constructed in several parts. Furthermore, the term "plate" is quite general to see, because even the support plates may have, for example, bulges or the like on its upper side, but at its bottom are expediently at least substantially planar. For grinding of curves or the like, it could also be provided that a grinding plate has an inner curvature or outer curvature at its respective working surface.

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 already explained projections and locking contours, including the actuating projection 140 which is radial with respect to the bayonet mount 129 or projects therefrom.

On the underside of the upper parts 184, 185, elastically deformable lower parts 186, 187 are arranged, for example adhesively bonded or fastened by means of a detachable connection, in particular a Velcro connection. Matching to the respective outer peripheral contours of the support plates 115, 116 and the lower parts 186, 187 are designed round or triangular. Carrier plates with other, e.g. elliptical or polygonal outer contours are also possible.

Attached to the underside of the bases 186, 187 are fasteners 180, such as hook-and-loop fasteners or the like, for releasably securing an abrasive or polishing agent.

It is understood that the carrier plates 115, 166 could also be integral and / or that they may integrally comprise a grinding or polishing agent.

On the underside of the support plates 115, 116 suction openings 181 are arranged, which communicate via top of the tools 24, 25 leading channels 182 with a suction 117b, which in turn is connected to the dust discharge channel 49, when the respective tool 24 or 25 in the hand Machine tool 10 is mounted.

• In dem Freirotation-Exzentermodus F kann im Prinzip ein an der Werkzeugaufnahme 23 befestigtes Werkzeug frei rotieren, so dass es bis zur Drehzahl der Antriebswelle 47 beschleunigt. Erst wenn das jeweilige Werkzeug ein Bremsmoment erfährt, beispielsweise beim Aufsetzen auf die zu bearbeitende Werkstück-Oberfläche, wird das Werkzeug abgebremst. Dadurch kann das Werkstück beschädigt werden. Die nachfolgend im Detail beschriebenen Bremsmittel wirken einer solchen "Autorotation" des Werkzeugs, das an der Werkzeugaufnahme 23 befestigt ist, entgegen. Sie könnten zwar im Prinzip bei dem dreieckförmigen Werkzeug 25 weggelassen werden, sind aber auch dort zur Unterstützung der Drehwinkel-Führungsmittel 67 zweckmäßig. Die nachfolgende Beschreibung konzentriert sich jedoch auf das Werkzeug 24.

At the top of the support plates 115, 116 seals 149 are arranged, which seal the suction space 117b in cooperation with the tool holder 23. However, the seals 149 have an additional function, which will become clear below:

• In principle, a tool fastened to the tool holder 23 can rotate freely in the free-rotation eccentric mode F, so that it accelerates up to the rotational speed of the drive shaft 47. Only when the respective tool experiences a braking torque, for example, when placed on the workpiece surface to be machined, the tool is braked. This can damage the workpiece. The braking means described in detail below counteract such "autorotation" of the tool, which is fastened to the tool holder 23. Although they could be omitted in principle in the triangular tool 25, but are also there to support the rotation angle guide means 67 appropriate. However, the following description focuses on the tool 24.

The inventively designed braking means comprise brake members 170 which are arranged on the tools 24 or 25, which cooperates with a machine-side rotationally fixed brake surface assembly 173. The brake member 170 is of the Seal 149 formed or, conversely formulated, the brake member 170 is annular and at the same time performs the function of a seal in connection with a dust removal from the working surface 41 away.

The braking surface arrangement 173 comprises a brake element 171b with a brake plate 171, from which a brake segment 172 protrudes at an angle, for example at right angles. One of the tool holder 23 facing inside of the brake segment 172 forms a radial braking surface 174, while the tool 24, 25 facing the end face of the brake plate 171 provides an end brake surface 175. The brake plate 171 is configured here as a ring body.

Furthermore, the brake element 171b is removably or releasably secured to the machine housing 11, for which purpose suitable fastening means, such as clamping means, screws or - as in the embodiment - locking means may be provided. For example, protruding from the brake element 171b, in particular the brake plate 171, radially outward projections 176, which are provided for engagement in corresponding recesses on the machine housing 11. On a side opposite to the projections 176, a latching hook 177 is provided on the brake plate 171, which engages with a latching receptacle 178 of the machine housing 11.

The tool 24 can rotate in the free rotation eccentric mode F about an axis of rotation, which in the present case is the drive axle 36. However, a radial braking surface 188 and a face braking surface 189 rub against the radial braking surface 174 or against the face braking surface 175 of the braking surface arrangement 173, so that a rotation of the tool 24 about the rotation axis 36 is braked. The face brake surfaces 175, 189 are always in frictional contact with each other, so that here achieves a constant braking effect becomes. The radial braking surface 174, however, extends only over a circular segment of a circle about the axis of rotation 36, for example about 120 °, so that the radial braking surfaces 174, 188 are in contact only when the tool 24, 25 due to the eccentricity 38 so to speak in the direction of the radial braking surface 174 is swinging. Thus, so the radial brake surface 174 forms, so to speak, a kind of auxiliary brake, which can be advantageously still adjustable, which in the embodiment according to FIGS. 9, 10 the case is.

Furthermore, it would also be possible to replace the brake element 171b with another brake element whose brake surfaces have a different geometry. For example, a brake element could be provided whose front brake surface has bulges or recesses. Furthermore, the geometric extent of the brake segment 172 could be different, so that, for example, is provided over a larger angle section or a smaller angle portion extending brake segment or a brake segment whose inner curvature does not match the radius of the brake member 170 on the outside.

It should also be noted that it is an expedient, but not mandatory embodiment of the invention that correspond to the radii of the brake segment 172 and brake member 170 in the region of their contact surfaces, but that also different radii of curvature are possible.

The brake surface assembly 173 expediently has a lower wear and thus a higher abrasion resistance than the brake member 170. The brake member 170 is now a part of the tool 24 or 25. If this wears out altogether, for example because the lower parts 186, 187 are worn, that is also Brake member 170 for replacement at. Thus, over a total operating time of a respective tool 24 or 25 a substantially constant braking effect can be achieved.

Contributing to this very uniform braking effect also that the brake member 170 is resilient both radially and axially with respect to the axis of rotation 36.

The brake member 170 is presently annular, but other, e.g. elliptical, brake links are conceivable.

Furthermore, the brake member 170 is centered to the machine holder 183, but also an eccentric arrangement is conceivable.

The brake member 170 includes a brake ring portion 190 that provides the radial brake surface 188 and the face brake surface 189. Thus, therefore, the brake ring portion 190 is a kind of bead, which is axially (with respect to the rotation axis 36), a free end of the brake member 170. On the face brake surface 189 also circular segment-like brake projections 191 are also provided, between which recesses 192 are arranged. The brake projections 191 form brake shoes, so to speak, which can gradually wear until the base of the brake ring portion 190 is reached. Through the recesses 192 interruptions in circumferential directions are present, can flow through the cooling air in the friction between brake member 170 and braking surface assembly 173, which counteracts overheating.

The radially outer periphery of the brake ring portion 190 is provided for brake contact with the radial braking surface 174. The radial braking surface 188 has a skew with respect to the drive axle 36 and with respect to the associated radial braking surface 174. Thus, therefore, the radial braking surface 188 is designed as a kind of circumferential projection, the corresponding abrasion and wear with respect to contact with the rotationally fixed radial braking surface 174 becomes wider.

The brake member 170 has due to a flexible material of which it consists, for example, a correspondingly soft plastic or rubber material, a certain flexibility, so that a readjustment or uniform braking effect can be achieved. In addition, however, flexibility is realized by a stage 193. Stage 193 is an axial stage, i. it is yielding parallel to the axis of rotation 36. As a result, the face brake surface 189 is always acted upon in the direction of the rotationally fixed face brake surface 175, so that the frictional contact is maintained.

Stage 193 is a perimeter tier. It forms part of an annular recess 194. The step 193 has a V-shaped cross-section. The step 193 is, so to speak, a lying step (in cross-section with respect to the axis of rotation 36) so that it is resiliently yielding against a pressing direction 195 (parallel to the axis of rotation 36). In FIG. 8 is a spring-loaded position 196 schematically indicated.

In particular, in the rebounded position 196, the brake member 170 can deform into a deformation recess 197 on the upper side of the tool 25. This measure is optional.

It is understood that differently configured stages, such as a Z-shaped axial step 198 or a likewise Z-shaped radial step 199 may be provided (in FIG. 8 indicated schematically). The radial step 199 is resilient radially to the axis of rotation 36 to improve contact with the radial braking surface 174.

It is understood that for cooperation with the tool 24, i. with an annular, according to the invention ausgestaltetem brake member, instead of the circular segment radial braking surface and a circumferentially closed radial braking surface (not shown) could be provided.

Step 193 includes a downward slope, i.e., an angle, of the axis of rotation 36; in the direction of the machine holder 183 and the top of the tool 24 extending inclined portion 200 which forms a leg of the V-shaped step 193. At the inclined portion 200 opens up with respect to the rotation axis 36 short bottom portion 201 at. The inclined portion 200 is a plant leg 202 of the stage 193 opposite.

The step 193 is followed by a radially inwardly open mounting recess 203, which serves for mounting the brake member 170 on the upper part 184. The mounting recess 203 is an annular groove, in the case of the upper part 185 engage individual latching hooks, while the upper part 184, however, a mounting bracket 204. The mounting bracket 204 includes an annular plate which serves as a ballast weight or balance weight. Thus, the weight ratios in both tools 24 and 25 are similar or the same.

The mounting bracket 204 comprises an annular plate with a central passage opening 205 for an annular body 206 of the bayonet receptacle 128. From the annular body 206 are the Hintergreifvorsprünge 130 radially inward from.

Further, the mounting bracket 204 has through holes 207 that mate with the channels 182 so that dust-laden air from the bottom can pass through the annular space defined by the gasket 159. The mounting bracket 204 could, for example, in the press fit or snap fit on the support plate 115th attached, but in the present case is screwed by means of screws 208.

The brake member 170 is, as it were, slipped over the radially outer edge or peripheral edge of the mounting bracket 204 by means of its mounting recess 203, so that the peripheral edge engages in the mounting recess 203. Even then, a firm grip of the brake member 170 is achieved on the mounting bracket 204. In addition, the brake member 170 is still pressed against the upper part 184, namely by a top 184 facing, in the drawing lower leg 209 between the mounting bracket 204 and the upper part 184 comes to rest. For the leg 209 a ring recess on the upper part 184 is expediently provided, but this is not absolutely necessary.

Instead of the fixed, non-adjustable brake surface assembly 173 can also in the FIGS. 9 and 10 shown brake surface assembly 220 are used.

The braking surface arrangement 220 according to this exemplary embodiment comprises a brake body 221, with a brake segment 222, whose end face facing the brake member 170 comprises a radial braking surface 224.

From the brake segment 222, which extends only over a partial circumference of a circle about the axis of rotation 36, is a retaining projection 223 from, in which a brake segment 222 of a brake adjusting 225 is screwed. The adjusting element 226 comprises a screw which is adjustable or screwable by means of a handle 227. The actuator 226 is a holder 228 screwed and penetrates this. Thus, by rotating the handle 227, the axial position of the adjusting element 226 can be adjusted radially to the axis of rotation 36, wherein the brake body 221 is entrained to along a Adjustment path 229 to the brake member 170 toward or away from this. As a result, the braking action of the radial braking surface 224 can be changed, preferably even completely canceled, when the brake body 221 is moved radially away from the braking 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.

During its rotation about the drive axle 36, the tool 25 and thus also the brake member 170 oscillates eccentrically due to the eccentricity 38, so that it inter alia assumes a braking position indicated by dashed lines, away from the radial braking surface 224 and shown in solid lines, in which it is in brake contact or frictional contact with the brake body 221. Thus, when the brake body 221 is moved along the adjustment path 229 further away from the rotation axis 36, this phase of the friction and braking engagement is shorter, so that the braking effect decreases. When adjusted to the axis of rotation 36 toward the braking effect of the brake body 221 is greater.

It is understood that also by other measures the braking effect could be changed, e.g. by changing the effective contact surface of the radial braking surface 224, which can be achieved for example by changing the radius of curvature thereof. If, for example, the circumferential end regions of the brake segment 222 are stationary, the middle section of the brake segment 222 could be adjusted by adjusting the adjusting element 226 along the adjustment path 229, thereby also changing the curvature of the radial braking surface 224.

Claims (13)

1. Hand-operated power tool, in particular grinding machine and/or polishing machine, with a drive motor (17) for driving a tool holder (23), with a disc tool (24; 25), in particular a backing pad or a polishing disc, attachable to the tool holder (23) by means of a machine mount (183), and with an eccentric gear (27) which has a drive shaft, rotary-coupled to the drive motor (17) and rotatable around a driving axis (36), to or on which is mounted by means of a tool shaft bearing (61, 62) a tool shaft (26) on which the tool holder (23) is mounted, to carry out eccentric movements around an eccentricity (38) eccentric to the driving axis (36), wherein the tool shaft (26) executes rotation movements in at least one rotation eccentric mode during rotation of the drive shaft, in particular on account of bearing friction of the tool shaft bearing (61, 62), wherein the tool holder (23) is provided with a non-rotatable braking contact surface arrangement (173, 220) to brake the disc tool (24; 25), wherein a brake member (170) of the disc tool (24; 25) mounted in particular on a supporting plate (115, 116) rubs on the braking contact surface arrangement (173, 220), and wherein in operation of the hand-operated power tool (10) the disc tool (24; 25) rotates around a rotation axis (36) relative to the non-rotatable braking contact surface arrangement (173, 220), wherein the braking contact surface arrangement (173, 220) has at least one radial brake contact surface (174, 224) which extends over a circle segment of a circle around the rotation axis (36), characterised in that the braking contact surface arrangement (173, 220) has at least one end brake contact surface (175) running at right-angles to, in particular perpendicular to, the rotation axis (36).
2. Hand-operated power tool according to claim 1, characterised in that the radial brake contact surface (174, 224) and the brake member (170) are in frictional engagement with one another over only a partial rotation of the disc tool (24; 25), owing to the eccentricity (38) of the tool holder (23) to the rotation axis (36).
3. Hand-operated power tool according to claim 1 or 2, characterised in that it has brake adjusting means (225) for adjustment of the braking effect of the radial brake contact surface (174, 224).
4. Hand-operated power tool according to claim 3, characterised in that the brake adjusting means (225) are designed for adjustment of the radial brake contact surface (174, 224) along an adjustment track (229) at right-angles to the rotation axis (36) and/or for adjustment of a curvature of the radial brake contact surface (174, 224) and/or for adjustment of a circumferential length of the radial brake contact surface (174, 224).
5. Hand-operated power tool according to claim 4, characterised in that the adjustment track (229) of the brake adjusting means (225) is adequate for an adjustment of the radial brake contact surface (174, 224) outside the range of the brake member (170) during rotation around the rotation axis (36) including the eccentricity (38).
6. Hand-operated power tool according to any of the preceding claims, characterised in that the radial brake contact surface (174, 224) is spring-loaded towards the brake member (170) and/or is located on a spring-elastic braking body.
7. Hand-operated power tool according to any of the preceding claims, characterised in that the radial brake contact surface (174, 224) is arranged radially inwards or radially outwards relative to the brake member (170).
8. Hand-operated power tool according to any of the preceding claims, characterised in that the end brake contact surface (175) has constant frictional contact with the brake member (170) for a constant braking effect.
9. Hand-operated power tool according to any of the preceding claims, characterised in that the braking contact surface arrangement (173, 220) is provided on a brake element (171 b) which is mounted releasably on a machine housing (11) of the hand-operated power tool (10) with the aid of attaching means (176, 177).
10. Hand-operated power tool according to any of the preceding claims. characterised in that the brake member (170) of the disc tool (24; 25) has at least one step (193) spring-loaded in a direction of pressure (195) towards the braking contact surface arrangement (173, 220).
11. Hand-operated power tool according to any of the preceding claims, characterised in that the brake member (170) is mounted, in particular by an end face, on a supporting plate (115, 116) of the disc tool (24; 25) or that the brake member (170) is formed by the supporting plate (115, 116) of the disc tool (24; 25).
12. Hand-operated power tool according to any of the preceding claims, characterised in that the brake member (170) is annular, in particular circular-arcshaped.
13. Hand-operated power tool according to any of the preceding claims, characterised in that the brake member (170) is in the form of a seal (149) which, in contact with the braking contact surface arrangement (173), in particular in cooperation with the tool holder (23), bounds a suction chamber (117b).

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