EP1216117A1

EP1216117A1 - Motor-powered portable grinding machine

Info

Publication number: EP1216117A1
Application number: EP01960139A
Authority: EP
Inventors: Steffen Tiede; Joerg Dehde; Dieter Weninger
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2000-09-23
Filing date: 2001-08-02
Publication date: 2002-06-26
Anticipated expiration: 2021-08-02
Also published as: EP1216117B1; US6726553B2; DE10047202A1; WO2002024408A1; US20020193055A1; JP2004508961A

Abstract

The invention relates to a motor-powered portable grinder (10), especially an eccentric plate grinder, having a work spindle (13) mounted in a machine casing (11) and a rotatable grinding plate unit (15) driven by said spindle to perform an eccentric movement. The portable grinder (10) also has a first ring-shaped pitch surface (30) that, together with the grinding plate unit (15), surrounds the eccentric axis (19) and a second ring-shaped pitch surface (30) assigned to the first pitch surface, the central axis of said second pitch surface extending coaxially relative to the central axis (17) of the work spindle (13) and the first pitch surface (28) being able to roll on said spindle. The second pitch surface (30) is rotationally mounted about its central axis. A braking device (35) is assigned to said second pitch surface by means of which rotation of the second pitch surface (30) about its central axis can be selectively stopped for forced drive or can be released to enable freewheeling.

Description

Motor-driven hand grinder

State of the art

The invention relates to a motor-driven hand-held grinding machine, in particular an eccentric disc grinding machine, according to the preamble of claim 1.

A hand-held grinding machine of this type is known (EP 0 245 850 A2), in which the first rolling surface is designed as an outer toothed ring which rotates around its axis with the driven grinding plate, and in which the second rolling surface consists of an inner toothed ring on one External gear rim is formed, which is held in a rotationally fixed manner with respect to the machine housing and is axially adjustable between an inactive position and a functional position interacting with the first rolling surface by means of an external actuating device. In the inactive position, the second rolling surface is out of engagement with the first rolling surface. In the functional position, on the other hand, the second rolling surface runs approximately in the same dimensional plane as the first rolling surface, so that the first rolling surface can roll on the second rolling surface when the grinding plate rotates, so that the eccentric movement of the grinding plate rotates it around its eccentric axis Movement is superimposed. This means that when the second rolling surface is in the functional position, increased workpiece abrasion can be achieved. The disadvantage of this hand grinder is that the switch between idle and positive drive is not is possible during operation of the hand grinder. Axial relative displacement can result in damage to the teeth of both rolling surfaces. Another disadvantage is a relatively large overall height of the grinding machine caused by this arrangement of the rolling surfaces.

Advantages of the invention

The motor-driven hand-held grinding machine according to the invention, in particular an eccentric disc grinding machine, with the features of claim 1 has the advantage over the prior art that a switch between freewheeling and forced driving during operation of the hand-held grinding machine is possible without the risk of damage, and there is a reduced overall height with little gear expenditure ,

Advantageous further developments and improvements of the motor-driven hand-held grinder specified in claim 1 are possible through the measures listed in the further claims.

According to an advantageous embodiment, the actuating device actuates the brake member, for. B. manually operable, eccentric lever with an eccentric acting on the brake member.

Here, the eccentric lever can be pivoted in the machine housing and have an eccentric pin as an eccentric, which in an opening, for. B. in a loop at the end of the brake member, in particular a brake band, which wraps around the outer peripheral surface of the outer ring gear, engages.

In a further advantageous embodiment, the eccentric lever has a handle for pivoting actuation located outside the machine housing. It can be advantageous that the eccentric lever is designed in such a way that the brake band is tensioned by pivoting through a circumferential angle of approximately 180 °. The handle of the eccentric lever can thus easily be swiveled between two positions when passing through a circumferential angle of 180 ° and the changeover between positive drive and freewheel can also be carried out while the hand grinder is in operation.

In a further advantageous embodiment of the invention, the outer toothed ring part, in particular one-piece part, the grinding plate unit, for. B. integral part of the SchleiftelJfer itself, on which the outer ring gear is molded. This is particularly simple and inexpensive and also contributes to a reduction in the overall height.

According to a further advantageous embodiment, the inner toothed ring of the outer toothed ring has a larger number of teeth than the outer toothed ring. The difference in the number of teeth can e.g. B. 2. This ensures that the grinding plate is driven at a predetermined speed in the forced drive setting. For example, B. the number of vibrations 10,000, the number of teeth ratio of 50:48 in the positive drive results in a grinding wheel speed of 417 rpm. According to a further advantageous embodiment, the grinding plate unit has a sleeve coupled to the work spindle, in particular connected in a rotationally fixed manner, with a z. B. end-side eccentric pin and a grinding plate held on the latter by means of a bearing, the z. B. is releasably connected to the eccentric pin by means of a screw.

It can also be advantageous if the external toothed gear has a bearing ring located along the central axis at an axial distance from the inner toothed ring and is rotatably mounted with the bearing ring by means of a bearing with respect to the sleeve coaxial with the axis of the work spindle. The camp can e.g. B. be pressed onto the sleeve, the outer ring gear being pressed with its bearing ring onto the outer ring of the bearing.

In a further advantageous embodiment, a fan wheel of an internal dust extraction is attached to the sleeve. As an alternative to this, the fan wheel can also sit directly on the work spindle in a rotationally fixed manner and have a sleeve which is eccentric with respect to the spindle axis and in which a cylindrical sleeve is rotatably supported by means of a bearing for holding the grinding plate at the end.

In a further advantageous embodiment, the sleeve with an eccentric pin at the end is formed from a sintered part and is thus designed to be particularly cost-effective. It can also be advantageous if the external toothed ring is formed from a light metal or zinc die-cast part, as a result of which an inexpensive design is also realized. In another advantageous embodiment of the grinding plate is integral with the order, the first rolling surface forming the outer ^• toothed wheel in a one-piece plastic injection molded part formed tion whereby a further Kostenreduzie- and simplification is achieved.

A further advantageous embodiment provides that the brake member relative to the machine housing can be fixed in a first position in which it is in positive engagement with the second rolling surface and in a second position in which it is in no engagement with the second rolling surface stands. It is particularly advantageous that the braking device can be switched between the first and second position and vice versa in all operating states, in particular when idling, at a standstill and under load.

It is particularly advantageous if the brake member is a band with several teeth, in particular a toothed belt, which can be brought into engagement with a ring gear of the second rolling surface. In contrast to a pure frictional engagement, there is no slippage between the braking device and the second rolling surface. This prevents wear of the two interlocking parts and prevents heat from developing.

It when the brake member is designed as an elastic band, in particular as a toothed belt, is particularly advantageous. Switching from freewheeling to forced driving is possible easily and with little tolerance due to such an elastic intermediate coupling. The brake member, in particular the elastic element, is preferably connected to the machine housing such that it can rotate about a fixed axis of rotation at a fixing point. As a result, when the elastic element is moved between the first and second positions, it is not necessary to kink the elastic band, which means little wear.

It is advantageous if the braking device has a locking lever which is connected to the machine housing via a spring element, in particular if the spring element tries to push the locking lever into a position in which the elastic element assumes its first position. Such an embodiment is mechanically simple to implement and is nevertheless sufficiently stable so that it is not operated incorrectly.

Furthermore, it is advantageous if the brake member is made of resilient material and has a first shaped area with a toothing which can be brought into engagement with the outer peripheral surface and a second shaped area, the brake member being held in its first position by a pretension and brought into its second position by an actuator. is. This makes it possible to use a simple part, for example a stamped part, as a braking member. This results in an inexpensive solution. In addition, such a configuration enables simple actuation with a low actuating force. This configuration acts both as overload protection for forced operation and as a shock absorber. It takes up little space; in addition, a compensation of Division errors of the transmission part, for example due to wear of the same.

Furthermore, it is advantageous if the locking lever can be displaced by an eccentric bolt which is rotatably mounted on the machine housing and can be operated by means of the actuating device which projects out of the machine housing. Switching between the two positions of the elastic element is thus very easy for the operator without having to switch off the device, regardless of the operating state it is in at the moment. H. both in free-running mode (fine sanding) and in forced driving mode (coarse sanding).

Furthermore, it is advantageous if the fixing point and the eccentric bolt are substantially diametrically opposite with respect to the central axis and the angle between the fixing point and the teeth of the elastic element, which are in engagement with the second rolling surface in the first position, is greater than 90 ° is. This prevents snapping under load.

Furthermore, it is advantageous if the fixing point and the eccentric bolt are substantially diametrically opposed with respect to the central axis and the cooperating surfaces of the braking member and the second rolling surface under load, similar to a servo effect, increase the holding force. As a result, a large holding force is generated with little effort, which increases the reliability of the device. ^'' Furthermore, it is advantageous if the braking device can be switched between the first and second positions and vice versa in all operating states, in particular when idling, at a standstill and under load. As a result, it is not necessary to first switch from one operating state to another in order to enable switching between the first and second positions. • This leads to time savings and greater comfort for the operator.

Further advantages and details of the invention are the subject of the dependent claims.

drawings

The invention is described in more detail below with reference to two exemplary embodiments shown in the drawings. Show it:

1 -i, a schematic section through a first embodiment of a hand grinder,

2 is a schematic plan view of parts of a braking device of the hand grinder in the plane II-II in Fig. 1, Fig. 3 is a schematic, partial section along the line III-III in Fig. 1,

4 shows a schematic bottom view of parts of the hand grinder in the direction of arrow IV in FIG. 1 without a grinding plate, FIG. 5 shows a schematic section through a second exemplary embodiment of a hand grinder, 6 shows a schematic section along the line AA in FIG. 5, the braking device not being in engagement with the second rolling surface,

Fig. 7 is a schematic section as in Fig. 6, wherein the braking device is in engagement with the second rolling surface and

Fig. 8 is a schematic partial view of a third embodiment of a braking device.

Description of the embodiment

1 schematically shows a first exemplary embodiment of a motor-driven hand-held grinding machine 10, which is designed here as an eccentric disc grinding machine. The hand grinder 10 has a machine housing, generally designated 11, which contains an electric drive motor 12 with a work spindle 13, which by means of a bearing 14, for. B. in the form of a ball bearing is mounted in the machine housing 11. A grinding plate unit, generally denoted by 15, is rotatably connected to the work spindle 13 and is driven by the work spindle 13 to an eccentric movement and is rotatable. The grinding plate unit 15 has a sleeve 16 which is non-rotatably and axially connected to the work spindle 13. The sleeve 16 extends coaxially to the central axis ^' 17 of the work spindle 13 and z. B. at the lower end in Fig. 1 an eccentric pin 18, the eccentric axis 19 with eccentricity e to the central axis 17 and parallel to this. On the eccentric pin 18 is by means of a bearing 20, for. B. a ball bearing, a grinding plate 21 rotatably mounted. The grinding plate 21 is by means of an eccentric axis 19 coaxial screw 22, which is screwed into the eccentric pin 18, axially fixed but rotatably connected to the sleeve 16 and the eccentric pin 19 and can be removed by loosening the screw 22. Between the machine housing 11 and the upper side of the grinding plate 21 in FIG. 1 there is a sleeve 23 sealing the intermediate space. The hand-held grinding machine 10 is equipped with an internal dust extraction, to which a fan wheel 24 belongs, which is held on the sleeve 16 in a rotationally fixed manner. The fan wheel 24 is located in a chamber 25 to which a dust extraction duct 26 is connected. The grinding plate 21 is provided with channels and / or openings 27 for the internal dust extraction.

The hand grinding machine 10 has an annular first rolling surface 28 which rotates together with the grinding plate unit 15 about the eccentric axis 19 and which is designed here as an outer toothed ring 29. This outer toothed ring 29 can be an independent component, for. B. gear represent, which is rotatably connected to the sleeve 16. In the exemplary embodiment shown, the toothed ring 29 is, in a particularly simple manner, part, in particular a one-piece part, of the grinding plate unit 15, and here in particular the grinding plate 21, which in this one-piece design is advantageously formed from a plastic injection-molded part. The first rolling surface 28, in particular the outer toothed ring 29, is assigned an annular second rolling surface 30 which surrounds the first rolling surface 28 and whose central axis runs coaxially with the central axis 17 of the work spindle 13. On the second rolling surface 30, the first rolling surface 28 can be Roll the drive motor 12. The second rolling surface 30 is preferably designed as an inner toothed ring 31 of an outer ring gear 32. ^' The second rolling surface 30, in particular the outer ring gear 32 which supports it, is rotatably mounted about the central axis 17. In the first exemplary embodiment shown, the outer ring gear 32 has a bearing ring 33 of smaller diameter arranged along the central axis 17 at an axial distance from the inner ring gear 31, via which the outer ring gear 32 by means of a bearing 34, for. B. a ball bearing, is rotatably mounted on the sleeve 16 relative to this. The inner ring of the bearing 34 is non-rotatably connected to the sleeve 16, while the outer ring of the bearing 34 is non-rotatably connected to the bearing ring 33 and thus to the outer ring 32.

The second rolling surface 30 is assigned a braking device, generally designated 35, by means of which a rotation of the second rolling surface 30 about its central axis, i. H. around the central axis 17, can optionally be prevented or released. The arrangement is such that the rotatability of the second rolling surface 30, in particular of the external ring gear 32, can be prevented or released by means of the braking device 35 during machine operation.

The external ring gear 32 is designed as a one-piece component and advantageously consists of a light metal die-cast part. The sleeve 16 with the eccentric pin 18 at the end is advantageously formed from a sintered part.

In the first exemplary embodiment shown, the fan wheel 24 is rotatably fixed as part of the internal dust extraction on the sleeve 16 arranged. In another exemplary embodiment, not shown, the fan wheel 24 is instead formed on a fan sleeve which is arranged in a rotationally fixed manner on the work spindle 13 and which has an inner sleeve which is eccentric to the central axis 17 and in which a bearing is coaxial with the eccentric axis 19 cylindrical sleeve similar to the sleeve 16 is rotatably and axially fixed, on the end of the grinding plate 21 is releasably attached by means of the screw 22.

The brake device 35 has a rolling surface to the second ^'30 acting as a brake braking member 36 and an actuator 37 for actuating the brake member 36th The brake member 36 is provided with a braking surface 38, with which the braking member 36 can engage flatly to prevent rotation of the second rolling surface 30 on an associated surface 39 of the second rolling surface 30, this surface 39 being designed in particular as an outer surface of the external ring gear 32. The second rolling surface _j 30 extends outside and surrounds the first rolling surface 28, both of which essentially extend within a common plane that is diametrical to the central axis 17 of the work spindle 13. The surface 39 of the second rolling surface 30 designed as an outer surface consists in particular of the outer peripheral surface 40 of the outer ring gear 32.

The brake member 36 generally consists of such a braking part, which, with its inner surface designed as a braking surface 38, can bear against the associated surface 39 of the second rolling surface 30, in particular on the outer peripheral surface 40 of the external ring gear 32, for rotational blocking. In a particularly simple design, the brake member 36 consists of a brake band that wraps around the outer circumferential surface 40 of the outer ring gear 32 and can be clamped against the outer circumferential surface 40 for rotational blocking.

The actuating device 37 has an eccentric lever which has a central part 41 which is pivotably mounted in the machine housing 11 and an eccentric pin 42 thereon which extends into an opening 43, for. B. a loop engages at one end of the brake member 36 designed as a brake band. On the central part 41, a handle 44 located outside the machine housing 11 engages for pivoting actuation. This actuating device 37, in the form of an eccentric lever, is designed in such a way that the brake member 36, which is designed as a brake band, is tensioned by pivoting the central part 41 by a circumferential angle of approximately 180 °. The tensioned position and thus the state of the outer ring gear 32 blocked against rotation is shown in FIG. 3. If the handle 44 is pivoted counterclockwise by approximately 18-0 ° into the position according to FIG. 2, the brake member 36 is relaxed in the form of the brake band, so that the external ring gear 32 is not blocked and therefore its rotation about the central axis 17, which also represents its central axis, is released.

In another, not shown embodiment, the actuating device 37 has a braking member 36 z. B. in the form of a brake band actuating, in particular the brake band exciting, magnets on, for. B. a controllable electromagnet. Another special feature of the hand-held grinding machine 10 is that the inner toothed ring 31 of the outer toothed ring 32 has a larger number of teeth than the outer toothed ring 29. The difference in the number of teeth can e.g. B. 2. This means that when braking

Outer ring gear 32, the outer toothed ring 29 rolling on its inner toothed ring 31 rotates one tooth per 180 ° eccentric movement and thus, with respect to the grinding plate 21 provided with the outer toothed ring 29, a speed of rotation occurs during the rolling. The speed of the grinding plate 21 is at an assumed number of vibrations of 10,000 and a number of teeth ratio of 50:48 z. B. 417 rpm.

If the braking device 35 is brought into the braking position according to FIG. 3 and the drive motor 12 is switched on, then the drive spindle 13 and the sleeve 16 together with the fan wheel 24 and any compensating masses (not shown here in particular) are rotatably driven, e.g. For example, with about 10 ^'000 U / min. In the exemplary embodiment shown, the drive from the work spindle 13 takes place directly on the sleeve 16. In another exemplary embodiment, not shown, a transmission is interposed instead. Because of this drive movement, the grinding plate 21 is driven such that, in addition to the eccentric movement, there is a rotation about the eccentric axis 19, which results in an eccentric rotary movement of the grinding plate 21. Due to the active braking device 35, the outer ring gear 32 is prevented from rotating, so that the outer toothed ring 29 can roll on the inner toothed ring 31 during rotation. At this stage thus a forced drive of the grinding plate 21 additionally about the eccentric axis 19.

If the brake member 36 is now in the non-braking state according to FIG. 2, the outer ring gear 32 can be freely rotated about the central axis 17 due to the bearing by means of the bearing 34 on the sleeve 16. The outer ring gear 32 can now also rotate due to the friction in the bearing 34. Depending on the friction conditions, there is a relative movement of the external ring gear 32 in the opposite direction of rotation to the grinding plate 21. The speed of the grinding plate 21 depends on the load on the base, i. H. of how firmly the hand grinder 10 with the Schleiftel- 1er 21 and one detachable thereon, e.g. B. by Velcro, attached sanding sheet is pressed against a workpiece to be machined. The speed of the grinding plate 21 can also be zero, depending on the circumstances. At this stage, the freewheeling operation results for the hand grinder 10.

During operation of the switched-on hand grinder 10, this freewheeling operation can be switched back to the forced drive by actuating the braking device 35.

The described hand grinder 10 is simple, compact and inexpensive. It allows in a simple way by lever operation, or in another embodiment not shown, by actuation of a magnet during the operation of the ^'machine a switch to a continuous transition from forced rotation to freewheel. The fact that the Outer toothed ring 29 is molded onto a ring part of the grinding plate 21 as a one-piece part, there is the advantage of reduced components and low height. Another advantage is the low expenditure for the implementation of the gear transmission, consisting of an outer toothed ring 29 and an inner toothed ring 31.

5 schematically shows a second exemplary embodiment of a motor-driven hand grinder 10. The drive of the grinding plate unit 15 and this grinding plate unit 15 itself are in principle constructed in the same way as that of the first exemplary embodiment. A work spindle 13 is rotatably driven by a drive motor 12, not shown, about a central axis 17. At its output end, the work spindle 13 has an eccentric pin 18. This forms an eccentric axis 19. A first rolling surface 28 is formed concentrically around the eccentric axis 19 and engages with its outer toothed ring 29 in an inner toothed ring 31 of a second rolling surface 30 which is arranged concentrically around the central axis 17. The grinding plate unit 15 is connected via a coaxial screw 22 * to an output shaft 4 which is arranged coaxially around the eccentric axis 19. The parts described work like those of the first embodiment, so that reference is made to the description there.

In contrast to the first exemplary embodiment, the outer circumferential surface 40 of the second rolling surface 30 is not essentially smooth, but has a ring gear 8. The brake member 36 is designed as an elastic element 7 and with teeth 2, in contrast to the essentially smooth brake member 36 of the first embodiment, which are opposite the ring gear 8.

The spatial arrangement between the teeth 2, which are formed on the side of the elastic element 7 opposite the ring gear 8, can be clearly seen in FIG. 6. The elastic element 7 is shown here in its second position, in which its teeth 2 are not in engagement with the ring gear 8 of the second rolling surface 30. As a result, the second rolling surface 30 can run freely in this decoupled position. This means that the grinding plate 21 only carries out an oscillating movement and a slight rotary movement, depending on the bearing friction in the bearing 20. The hand grinder 10 is thus in the fine grinding mode. The higher the bearing friction, the stronger the turning movement. The elastic element 7 has at one end a fixing point 3 which is connected to the machine housing 11 via a fixed axis of rotation 5. At its other end, the elastic element 7 is designed as a locking lever 6. The locking lever 6 is actuated by means of an eccentric bolt 1, which is connected to an actuating device 37 (not shown) according to the first exemplary embodiment. The locking lever 6 is constantly pressed against the eccentric pin 1 by a spring element 9, which is supported on the machine housing 11. The teeth 2 on the elastic element 7 are formed closer to the locking lever 6 than at the fixing point 3. The fixing point 3 and the locking lever 6 are arranged essentially diametrically to the central axis 17. For the angle o: between the fixing point 3 and the teeth 2, this means that it is greater than 90 °. This not only prevents the teeth 2 from snapping against the ring gear 8 under load, but also prevents it a holding force between the teeth 2 and the ring gear 8 is increased in the manner of a servo effect.

7 shows the elastic element 7 in its first position. The teeth 2 of the elastic element 7 engage positively in the toothed ring 8 on the outer circumferential surface 40 of the second rolling surface 30. A forced entrainment is thus achieved and the hand grinder 10 operates in the rough grinding mode. The oscillating movement of the grinding plate 21 is forced a rotational movement. Due to the positive engagement between the teeth 2 and the ring gear 8, there is no slippage between the braking device 35 and the second rolling surface 30, so that the wear and the heat development go to zero. The engagement between the teeth 2 and the ring gear 8 is brought about during the transition from the second position (FIG. 6) to the first position (FIG. 7) in that the eccentric pin 1 is moved from its inside by means of the actuating device 37, not shown Fig. 6 position is transferred to its position shown in Fig. 7. For the movement of the eccentric bolt 1 from its position shown in FIG. 7 to its position shown in position 6, the statements made for the first embodiment apply accordingly. The spring element 9 constantly presses the locking lever 6 against the eccentric bolt 1. Since one end of the elastic element 7 is rotatably mounted about the fixed axis of rotation 5, the elastic element 7 is moved closer to the second rolling surface 30 until the positive engagement takes place. The eccentric pin 1 is moved by approximately 4 ° with respect to the central axis 17. The operator thus has the option of changing from fine sanding mode to coarse sanding mode using a shift lever without having to switch off the machine. Switching from freewheeling to forced driving can be switched in all operating states, ie idling, standstill and under load, by means of a described elastic intermediate coupling. The switchover is also simple and involves little tolerance.

In Fig. 8 elastic element 7 is formed in a particularly simple to implement embodiment. It is shown in its first position. The elastic element 7 is designed as a molded part made of spring steel, which is essentially in the form of a circular arc. At its first end 51, it is in a torsion spring joint 50, which is rigid with the machine housing (not shown). The elastic element 7 has a first shaped region 45 which is designed as a toothing 46. In the exemplary embodiment shown, these are two teeth. However, just one tooth as well as more than two teeth, for example three or four teeth, are just as possible. The elastic element 7 is clamped in the torsion spring joint 50 such that, due to its spring force, its toothing 46 presses against the ring gear 8 of the outer circumferential surface 40 of the second rolling surface 30. The ring gear 8 snaps into the toothing 46 of the elastic element 7. This form-fitting connection can be released in that a force 49 is exerted on the second end 48 of the elastic element 7, which cancels the latching by moving the toothing 46 away from the ring gear 8. This takes place against the spring force of the elastic element 7 due to its clamping in the torsion spring joint 50. see element 7 has, in addition to the first shaped area 45, a second shaped area 47. This second shaped area 47 has a tangential elasticity and thus serves as a torsion shock suspension.

Such a configuration of the braking device 35 is very simple and inexpensive. It can be actuated very easily using a low actuation force and furthermore has a torsional shock absorption and an overload protection for the forced operation. In addition to the advantage of a small space requirement, they can compensate for pitch errors in the transmission part, which are caused, for example, by wear.

Reference character list

1 eccentric bolt

2 teeth

3 fixation point

4 output shaft

5 fixed axis of rotation

6 locking levers

7 elastic element

8 sprocket

9 spring element

10 hand grinder

11 Masc in housing

12 drive motor

13 drive spindle

14 bearings

15 sanding disc unit

16 sleeve

17 centric axis

18 eccentric pins

19 eccentric axis

20 bearings

21 sanding plates

22 coaxial screw

23 cuff

24 fan wheel

25 chamber

26 dust extraction duct

27 breakthrough

28 first rolling surface

29 outer ring gear

30 second rolling surface

31 inner ring gear

32 external ring gear Bearing ring Bearing Braking device Brake link Actuating device Braking area Surface outer circumferential surface Central part of eccentric pin Opening Handle First formed area Gearing Second formed area Second end Force torsion spring joint First end

Claims

Expectations

1. Motor-driven hand grinding machine, in particular an eccentric disk grinding machine, with a work spindle (13) mounted in the machine housing (11) and a grinding disk unit (15) which is driven and rotatable by this to an eccentric movement, and with a grinding disk unit (15) together with the grinding disk unit (15) around the eccentric axis (19) circumferential annular first rolling surface (28) on the one hand and an annular second rolling surface (30) associated therewith, on the other hand

Central axis runs coaxially to the central axis (17) of the work spindle (13) and on which the first rolling surface (28) can roll, characterized in that the second rolling surface (30) is rotatably mounted in a bearing (34) about its central axis and that the second rolling surface (30) is assigned a braking device (35), by means of which rotation of the second rolling surface (30) about its central axis can be selectively prevented or enabled.

2. Motor-driven hand grinder according to claim 1, characterized in that the rotatability of the second rolling surface. (30) can be prevented or released by means of the braking device (35) during machine operation.

3. Motor-driven hand grinder according to one of the preceding claims, characterized in that the braking device (35) has a braking member (36) which acts on the second rolling surface (30) and a braking actuation device (37) for actuating the brake member (36).

4. Motor-driven hand grinder according to one of the preceding claims, characterized in that

Braking member (36) has a braking surface (38) with which the braking member (36) can engage flatly on an associated surface (39) of the second rolling surface (30), in particular on an outer surface, to block the second rolling surface (30). .

5. Motor-driven hand grinder according to one of the preceding claims, characterized in that the second rolling surface (30) extends on the outside and surrounds the first rolling surface (28) and that both rolling surfaces

(28, 30) extend essentially within a common plane diametrical to the axis (17) of the work spindle (13).

6. Motor-driven hand grinder according to one of the preceding claims, characterized in that the second rolling surface (30) is designed as an inner toothed ring (31) of an external toothed ring (32) and the first rolling surface (28) is designed as an outer toothed ring (29).

7. Motor-driven hand grinder according to one of the preceding claims, characterized in that an outer surface, in particular an outer peripheral surface (40) of the second rolling surface (30), in particular of the external toothed ring (32), as with the braking member (36).

Rotary blocking cooperating surface is formed.

8. Motor-driven hand grinder according to one of claims 3 to 7, characterized in that the beta actuation device (37) a magnet actuating the braking member (36), in particular a controllable electromagnet, or a z. B. has a manually operated eccentric lever with an eccentric (42) acting on the brake member (36).

9. Motor-driven hand grinder according to one of claims 3 to 8, characterized in that the braking member (36) of the braking device (35) has an inner surface designed as a braking surface (38) on the associated surface (39), in particular on the outer U - peripheral surface (40) of the external gear ring (32), can rest to block rotation.

10. Motor-driven hand grinder according to one of claims 3 to 9, characterized in that the brake member (36) is formed from a brake band which is used to block rotation against the surface (39), in particular the outer peripheral surface (40) of the external toothed ring (32), can be tensioned.

11. Motor-driven hand grinder according to one of the preceding claims, characterized in that the braking member (36) to the machine housing (11) is in a first position in which it is connected to the second rolling surface

(3'0) is in a positive engagement, and can be fixed in a second position in which it is not in engagement with the second rolling surface (30).

12. Motor-driven hand grinder according to claim 11, characterized in that the braking member (36) is a band with several teeth (2), in particular a toothed belt, which can be brought into engagement with a toothed ring (8) of the second rolling surface (30).

1 . Motor-driven hand grinder according to claim 11 or 12, characterized in that the braking member (36) is designed as an elastic element (7), in particular as a toothed belt.

14. Motor-driven hand grinder according to one of claims 11 to 13, characterized in that the braking member (36), in particular the elastic element (7), can be rotated with the machine housing (11) at a fixing point (3) about a fixed axis of rotation (5). connected is .

15. Motor-driven hand grinder according to one of claims 11 to 14, characterized in that the braking device (35) has a locking lever (6) which is connected to the machine housing (11) via a spring element (9).

16. Motor-driven hand grinder according to claim 15, characterized in that the spring element (9) tries to press the locking lever (6) into a position in which the elastic element (7) assumes its first position.

17. Motor-operated hand grinder according to one of claims 11 to 16, characterized in that the braking member (36) is made of resilient material and has a first shaped region (45) with teeth (46) which is connected to the outer peripheral surface (40 ) can be brought into engagement and a second shaped region (47), wherein the braking member (36) is held in its first position by a preload and can be brought into its second position by an actuating device (37).

18. Motor-driven hand grinder according to one of claims 11 to 17, characterized in that the locking lever (6) can be moved by an eccentric bolt (1) which is rotatably mounted on the machine housing (11).

5 and can be operated by means of the actuating device (37) protruding from the machine housing (11).

19. Motor-driven hand grinder according to one of claims 14 to 18, characterized in that

10 the fixing point (3) and the eccentric bolt (1) are essentially diametrically opposite with respect to the central axis (17) and the angle (α) between the fixing point (3) and the teeth (2) of the elastic element (7), which in the first position engaged with

15 of the second rolling surface (39) is larger than 90 °.

20. Motor-driven hand grinder according to one of claims 14 to 19, characterized in that the fixing point (3) and the eccentric bolt (1) relate to each other.

20 lies essentially diametrically opposite the central axis (17) and the interacting surfaces of the brake member (36) and the second rolling surface (30) increase the holding force under load, similar to a servo effect.

25

21. Motor-driven hand grinder according to one of claims 11 to 20, characterized in that the braking device (35) in all operating states, in particular when idling, at a standstill and under load, between

^'30 see the first and second position and vice versa can be switched.