CN108115621B

CN108115621B - Portable power tool, tool holder and method for the oscillatory driving of a tool holder

Info

Publication number: CN108115621B
Application number: CN201711213239.7A
Authority: CN
Inventors: J·齐格尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2016-11-28
Filing date: 2017-11-28
Publication date: 2022-09-20
Anticipated expiration: 2037-11-28
Also published as: EP3330044A1; CN108115621A; DE102016223508A1; EP3330044B1

Abstract

The invention relates to a portable power tool, in particular a grinding machine, comprising: at least one oscillatably drivable tool receiving part (12 a; 12 b); at least one drive unit (14 a; 14b) having at least one drive shaft (16 a; 16b) for driving at least the tool receptacle (12 a; 12b), the drive shaft having at least one drive axis (18 a; 18b) intersecting the tool receptacle (12 a; 12 b); and at least one support unit (20 a; 20b) for movably supporting the tool receptacle (12 a; 12b) about a support axis (22 a; 22b) of the support unit (20 a; 20b), which intersects the tool receptacle (12 a; 12 b).

Description

Portable power tool, tool holder and method for the oscillatory driving of a tool holder

Technical Field

The invention relates to a portable power tool.

Background

Portable power tools, in particular grinding machines, are already known, having: at least one oscillatably drivable tool receiving portion; at least one drive unit having at least one drive shaft for driving at least the tool receiving portion, the drive shaft having at least one drive axis intersecting the tool receiving portion; and at least one support unit for movably supporting the tool receiver about a support axis of the support unit, the support axis intersecting the tool receiver.

Disclosure of Invention

The invention relates to a portable power tool, in particular a grinding machine, comprising: at least one oscillatably drivable tool receiver; at least one drive unit having at least one drive shaft for driving at least the tool receiving portion, the drive shaft having at least one drive axis intersecting the tool receiving portion; and at least one support unit for movably supporting the tool receiver about a support axis of the support unit, which support axis intersects the tool receiver.

It is proposed that the drive axis is configured differently from the bearing axis.

A "portable power tool" is to be understood here to mean, in particular, a power tool for machining a workpiece, which can be transported by an operator without a transport machine. The power tool is in particular designed as an electrically driven power tool. The power tool is in particular designed as a mains-operated power tool and/or preferably as a battery-operated power tool. The power tool has, in particular, a battery receptacle which is provided for receiving a battery for operating the power tool. The battery receptacle is arranged at least substantially in a handle of the power tool. For driving the power tool, the battery has in particular only one battery cell. The battery has in particular a volume of at most 0.9 liter, preferably at most 0.7 liter and particularly preferably at most 0.5 liter. The battery in particular has an electrical output of at least 50 watts, preferably at least 75 watts, and particularly preferably at least 100 watts. The portable power tool has a mass, in particular including a battery, of less than 700g, preferably less than 600g and particularly preferably less than 500 g. The machine tool has a nominal power of at least 50 watts, preferably at least 75 watts, and particularly preferably at least 100 watts. The ratio between the grip area and the total surface area of the machine tool is in particular between 0.4 and 0.9, but preferably between 0.5 and 0.75. The machine tool is preferably designed as a triangular grinding machine, a vibratory grinding machine or a multifunction grinding machine.

A "drive unit" is to be understood in this context to mean, in particular, a unit which is provided for converting, in particular, electrical energy into kinetic energy, in particular rotational energy. The drive unit has in particular at least one electric motor. The drive shaft of the drive unit is formed at least in part by an armature shaft of the electric motor. "provided" is to be understood in particular to mean specially designed, specially programmed, and/or specially equipped. The element and/or the unit is provided for a specific function, in particular it should be understood that the element and/or the unit fulfills and/or carries out the specific function in at least one application state and/or operating state. A "tool holder" is to be understood to mean, in particular, a device for coupling to a drive shaft, such as, in particular, a tool holder to which a sanding plate can be fastened (as is often the case in a triangular sanding machine), or a sanding plate itself that can be fastened directly to a drive shaft and to which a sanding sheet can be fastened (as is the case in a hand-held machine tool with an oscillating drive). The tool receptacle is preferably provided for receiving a plug-in tool, in particular a sanding sheet, in a repeatedly detachable manner by an operator. A drive axis extending at least substantially along a drive shaft of the drive unit, in particular along an armature shaft of an electric motor of the drive unit, intersects the tool receptacle at least substantially perpendicularly. The expression "substantially perpendicular" is intended here to define, in particular, an orientation of a direction relative to a reference direction, wherein the direction and the reference direction, in particular, as viewed in a plane, enclose an angle of 90 ° and the angle has a maximum deviation of, in particular, less than 10 °, advantageously less than 5 ° and, particularly advantageously, less than 2 °.

A "support unit" is to be understood in this context to mean, in particular, a unit which supports at least two components in a movable manner relative to one another. The bearing unit is provided in particular for mounting the tool holder in a movable manner relative to the machine tool housing. The bearing unit is in particular designed as a radial bearing unit. The bearing unit can be designed in particular as a sliding bearing unit and/or as a rolling bearing unit. The bearing unit is provided in particular for rotatably supporting the tool receiver about a bearing axis. The drive unit is provided in particular for driving the tool receiver in an oscillating manner about a bearing axis of the bearing unit. The support axis of the support unit intersects the tool receptacle at least substantially perpendicularly.

The drive axis is configured differently from the bearing axis, in this context it being understood in particular that the bearing axis and the drive axis are formed by two separate components. The drive axis and the bearing axis are formed in particular by two components which are spaced apart from one another. The bearing axis and the drive axis extend at least substantially spatially spaced apart from one another. The bearing axis extends in particular only along at least one component of the bearing unit. The drive axis extends in particular only along a component of the drive unit, in particular along a drive shaft of the drive unit. The bearing axis extends in particular along a component of the bearing unit, which component has no direct physical contact, in particular no material and/or form-locking, with a component of the drive unit forming the drive axis, in particular a drive shaft of the drive unit.

In accordance with this configuration, a power tool of the type mentioned at the outset can be provided which has advantageous structural and/or operational characteristics. In particular, an advantageous oscillatory driving of the tool holder about the bearing axis can be achieved by the bearing axis being configured separately from the drive axis.

It is also proposed that the bearing axis intersects the tool receptacle offset from the drive axis. The bearing axis and the drive axis intersect the tool receiver, in particular, at two points of intersection which are spaced apart from one another. The drive axis can intersect the tool receiver in particular at an intersection point which lies on a circle around the intersection point between the bearing axis and the tool receiver. The circle around the intersection between the bearing axis and the tool receiver can in particular have at least substantially any radius. The intersection point between the bearing axis and the tool receiver forms, in particular, at least substantially the middle point of the circle in which the intersection point between the drive axis and the tool receiver lies. Preferably, the drive axis intersects the tool receiver, viewed in the main working direction of the power tool, at an intersection point which is located in front of or behind the intersection point between the bearing axis and the tool receiver. The drive axis intersects the tool holder at an intersection point, in particular between a circle around the intersection point between the bearing axis and the tool holder and a main direction of extension of the machine tool. The tool receiver can thereby be advantageously driven and/or can be advantageously arranged on a base housing of the power tool. The use of a vibration element can advantageously be dispensed with by the offset arrangement of the bearing axis and the drive axis.

It is furthermore proposed that the drive axis extends at least substantially parallel offset to the bearing axis. "substantially parallel" is to be understood here to mean, in particular, an orientation of a direction relative to a reference direction, in particular in a plane, wherein the deviation of the direction relative to the reference direction is, in particular, less than 10 °, advantageously less than 5 ° and, particularly advantageously, less than 2 °. This makes it possible to achieve an advantageous arrangement and/or an advantageous course of the bearing axis and the drive axis, in particular in the machine tool.

It is also proposed that the bearing axis intersects the sanding plate at least substantially centrally. The bearing axis intersects the sanding plate at least substantially centrally, which is to be understood in particular to mean that the intersection point of the bearing axis with the tool receptacle at least substantially coincides with the center point of the tool receptacle. In particular, the intersection point of the bearing axis with the tool receiver deviates by a maximum of 5 mm, preferably a maximum of 2 mm, advantageously a maximum of 1 mm and particularly preferably a maximum of 0.5 mm from the center point of the tool receiver. The tool holder can advantageously be driven in an oscillating manner about the support axis without a vibration element by means of a central support and an eccentric drive of the tool holder.

Furthermore, it is proposed that the bearing unit has at least one bearing pin extending along a bearing axis, on which the tool holder is fastened so as to be rotatable about the bearing axis. The support tongue is in particular of at least substantially cylindrical design. The support tongue is in particular designed to be at least force-locked with the machine tool housing. The support tongues can be constructed in particular integrally with the machine tool housing. "integrally" is to be understood in particular as: at least a material-locking connection, for example by means of a welding process, an adhesive process, an additional injection molding process and/or other processes which are considered by the expert as being relevant; and/or, advantageously, integrally molded, for example by being manufactured by casting and/or by being manufactured in a single-component or multi-component injection method and advantageously from a single blank. The bearing axis extends in particular at least substantially along the main direction of extension of the bearing pin. The bearing unit preferably has at least one radial bearing, which is provided for rotatably supporting the sanding plate about a bearing axis. The radial bearing is arranged in particular at least partially and preferably completely on the bearing pin. The radial bearing can be designed in particular as a sliding bearing and/or preferably as a rolling bearing, in particular as a ball bearing. The radial bearing can be connected to the bearing pin, in particular by means of a press fit. The tool receptacle has, in particular, at least one receptacle, which is provided for at least partially receiving a radial bearing of the bearing unit. The tool receiver can thus advantageously be fixed to the machine tool in a simple and/or reliable manner so as to be rotatable about the bearing axis.

It is also proposed that the drive unit has a rolling bearing arranged eccentrically to the drive axis on the drive shaft, which rolling bearing is provided for transmitting a movement from the drive shaft to the tool receptacle. The rolling bearing is arranged in particular eccentrically on the drive shaft. During rotation of the drive shaft, the rolling bearing describes, in particular, an eccentric movement about the drive axis. The tool holder has in particular at least one running surface corresponding to a rolling bearing, by means of which the rolling bearing transmits a movement extending eccentrically about the drive axis to the tool holder. The tool holder has in particular at least one running surface which is provided for converting a movement of the rolling bearing into an oscillating movement of the tool holder about the bearing axis. The tool holder has in particular at least two running surfaces which are provided for converting a movement of the rolling bearing into an oscillating movement of the tool holder about the bearing axis. These working surfaces are in particular integrally formed with the tool holder. The working surfaces extend in particular at least substantially parallel to one another. A rolling bearing arranged eccentrically with respect to the drive axis on the drive shaft is provided in particular during rotation of the drive shaft for alternately loading the running surfaces with force. The alternating loading of the working surface is provided in particular for setting the tool holder in a swiveling motion. The tool receptacle can thereby be advantageously easily and/or efficiently set into an oscillating pivoting movement about the bearing axis. By the oscillating movement, the tip of the tool receptacle still describes a large course despite the small eccentricity. This makes it possible to achieve a high stock removal during grinding on the edge of the tool receptacle.

Furthermore, a tool holder, in particular a sanding plate for a power tool, is proposed, wherein the tool holder has at least one holder for a radial bearing, which is provided for mounting the tool holder in a rotatable manner about a bearing axis, and at least one running surface, which is provided for converting a movement of a rolling bearing into an oscillating movement of the tool holder about the bearing axis. This makes it possible to provide a tool holder with advantageous structural and/or operating characteristics. In particular, an advantageous oscillating drive of the tool holder about the bearing axis can be achieved. Furthermore, the tool holder can be driven in an oscillating manner about the bearing axis, advantageously without a vibration element.

Furthermore, a method for driving a tool holder in an oscillating manner is proposed, in which a movement of a rolling bearing arranged eccentrically to a drive axis on the drive shaft is converted into an oscillating movement of the tool holder about a bearing axis different from the drive axis. In particular, the tool holder is mounted at least substantially centrally so as to be rotatable about a bearing axis. The rolling bearing describes in particular an eccentric movement about the drive shaft during rotation of the drive shaft. In particular, a movement of the rolling bearing extending eccentrically around the drive axis is transmitted to the tool holder via at least one running surface, preferably at least two running surfaces. In particular, during rotation of the drive shaft, the running surface of the tool receiver is alternately acted upon by force by a rolling bearing arranged eccentrically with respect to the drive axis on the drive shaft. In particular, the tool holder is set into an oscillating pivoting motion about the bearing axis by the alternating loading of the working surfaces. The tool holder can thereby be advantageously easily and/or efficiently set in an oscillating pivoting movement about the bearing axis.

The power tool according to the invention, the tool holder according to the invention and/or the method according to the invention should not be limited to the above-described applications and embodiments. The machine tool according to the invention, the tool holder according to the invention and/or the method according to the invention can have a different number of individual elements, components and units and method steps than those mentioned here, in particular in order to satisfy the operating modes described here. Furthermore, the values within the mentioned limits are to be regarded as disclosed and can be used as desired in the context of the value ranges specified in the disclosure.

Drawings

Other advantages are obtained from the following description of the figures. Two embodiments of the invention are shown in the drawings. The figures, description and claims protect various combinations of features. The expert can treat or generalize these features individually as meaningful other combinations, as the purpose is.

Fig. 1 is a side view of a portable power tool, which is designed as a triangular grinder, with an oscillatingly drivable tool receiver,

figure 2 is a side sectional view of the portable power tool,

figure 3 is a top view of the underside of the tool receiving portion,

fig. 4 shows a side sectional view of an alternative portable power tool, an

Fig. 5 is a plan view of the underside of the tool holder of the machine tool according to fig. 4.

Detailed Description

Fig. 1 shows a side view of a portable power tool 10 a. Fig. 2 shows a side sectional view of the machine tool 10a from fig. 1. In the exemplary embodiment shown in fig. 1, the power tool 10a is designed as a grinding machine, in particular as a triangular grinding machine. However, it is likewise conceivable for the power tool 10a to have other configurations which are considered to be expedient by the person skilled in the art. The power tool 10a is designed as an electrically operated power tool 10 a. The power tool 10a is battery-operated. Alternatively or additionally, it is conceivable for the power tool 10a to be drivable in a cordless manner. The power tool 10a has a battery receptacle 40a, which is arranged in a housing 42a of the power tool 10 a. The housing 42a is in particular designed as a shell housing. The battery receptacle 40a is arranged in particular at least substantially in the handle 44a of the power tool 10 a. The battery receptacle 40a is provided for receiving a battery 46a for driving the power tool 10 a. The battery 46a preferably has only one battery cell. The accumulator 46a has, in particular, a volume of at most 0.9 liter, preferably at most 0.7 liter and particularly preferably at most 0.5 liter. The battery 46a has, in particular, an electrical output of at least 50 watts, preferably at least 75 watts, and particularly preferably at least 100 watts. The power tool 10a has, in particular, a mass which, in particular together with the battery 46a, is less than 700g, preferably less than 600g and particularly preferably less than 500 g. The power tool 10a has, in particular, a nominal power of at least 50 watts, preferably at least 75 watts, and particularly preferably at least 100 watts. The ratio between the grip surface 48a and the total surface 50a of the power tool 10a is in particular between 0.4 and 0.9, but preferably between 0.5 and 0.75.

The power tool 10a has an oscillatably drivable tool receiver 12 a. The tool receiver 12a is configured as a grinding plate 38 a. Preferably, the tool receiving portion 12a is provided for receiving a plug-in tool, in particular a sanding sheet, in a repeatedly detachable manner by an operator. Fig. 3 shows a plan view of the underside of the tool receiver 12 a. The power tool 10a also has a drive unit 14a for driving the tool receiver 12 a. The drive unit 14a has an electric motor 52a, which is provided to convert the electrical energy provided by the battery 46a into kinetic energy, in particular rotational energy. The drive unit 14a has a drive shaft 16a for driving at least the tool receiver 12a, which has a drive axis 18a intersecting the tool receiver 12 a. The drive shaft 16a is formed, in particular, at least in part by an armature shaft 54a of the electric motor 52 a. Furthermore, the power tool 10a comprises a support unit 20a for movably supporting the tool receiver 12a about a support axis 22a of the support unit 20a, which intersects the tool receiver 12 a. The bearing unit 20a is provided in particular for movably bearing the tool receiver 12a relative to the housing 42a of the power tool 10 a. The drive unit 14a is disposed in front of the support unit 20a within the housing 42 a. The drive axis 18a is configured differently from the bearing axis 22 a. The bearing axis 22a and the drive axis 18a extend at least substantially spatially apart from one another. The bearing axis 22a extends in particular only along at least one component of the bearing unit 20 a. The drive axis 18a extends in particular only along at least one component of the drive unit 14a, in particular along the drive shaft 16 a. The drive axis 18a extends at least substantially along the drive shaft 16a, in particular along an armature shaft 54a of the electric motor 52 a. The drive axis 18a extends at least substantially parallel offset relative to the bearing axis 22 a.

The bearing axis 22a intersects the tool receiver 12a offset from the drive axis 18 a. The bearing axis 22a intersects the tool receiver 12a at least substantially centrally. The bearing axis 22a and the drive axis 18a intersect the tool receptacle 12a at two

intersection points

56a, 58a which are spaced apart from one another in space. In particular, the drive axis 18a intersects the tool receiver 12a at an intersection point 56a, which is arranged on a circle 60a surrounding an intersection point 58a between the bearing axis 22a and the tool receiver 12 a. The drive axis 18a intersects the tool receiver 12a at an intersection point 56a between a circle 60a about the intersection point 58a between the bearing axis 22a and the tool receiver 12a and a main direction of extension 62a of the power tool 10 a. The drive axis 18a intersects the tool receiving portion 12a forward of the support axis 22 a.

The bearing unit 20a has a bearing pin 24a extending along a bearing axis 22a, to which the tool receiver 12a is fastened so as to be rotatable about the bearing axis 22 a. The support tongues 24a are at least substantially cylindrical in shape. The support tongue 24a is at least force-locked in particular to the housing 42a of the machine tool 10 a. The support tongue 24a may be formed in particular integrally with the housing 42a of the power tool 10 a. The bearing axis 22a extends in particular at least substantially along the main extension direction of the bearing tongue 24 a. The bearing unit 20a further comprises a radial bearing 26a, which is provided for rotatably supporting the tool receiver 12a about the bearing axis 22 a. A radial bearing 26a is arranged on the support tongue 24 a. The radial bearing 26a is designed as a rolling bearing, in particular as a ball bearing. The radial bearing 26a can be connected to the support tongue 24a, in particular, by means of a press fit. The tool receiving portion 12a has a receiving portion 34a which is provided for receiving the radial bearing 26 a.

The drive unit 14a has a rolling bearing 28a arranged eccentrically with respect to the drive axis 18a on the drive shaft 16 a. The rolling bearing 28a is in particular designed as a ball bearing. The rolling bearing 28a is provided for transmitting a movement from the drive shaft 16a to the tool receiver 12 a. The tool receiving portion 12a has two working

surfaces

30a, 32 a. These running surfaces are provided for converting the movement of the rolling bearing 28a into a pivoting movement 36a of the tool holder 12a about the bearing axis 22 a. The working

surfaces

30a, 32a are in particular formed integrally with the tool holder 12 a. The running surfaces 30a, 32a extend in particular at least substantially parallel to one another. During rotation of the drive shaft 16a, the rolling bearing 28a describes an eccentric movement about the drive axis 18 a. A rolling bearing 28a arranged eccentrically to the drive axis 18a on the drive shaft 16a is provided for alternately registering the running

surfaces

30a, 32a with force during rotation of the drive shaft 16 a. The alternating loading of the working

surfaces

30a, 32a is provided for setting the tool receiver 12a into a pivoting movement 36a about the bearing axis 22 a. The vibration element is not required by the central support and eccentric drive of the tool receiver 12 a. The tool receiver 12a is excited in an oscillating manner, so that the tip 64a of the tool receiver 12a describes a large path despite a small eccentricity. This makes it possible to achieve a high stock removal during grinding on the edge of the tool receptacle 12 a.

Another embodiment of the invention is shown in fig. 4 and 5. The following description and the figures are essentially limited to the differences between the exemplary embodiments, wherein reference can in principle also be made to the figures and/or descriptions of the other exemplary embodiments, in particular the exemplary embodiments of fig. 1 to 3, with regard to identically named components, in particular components bearing the same reference numerals. To distinguish between these embodiments, the embodiment in figures 1 to 3 is given the letter a after the reference numeral. In the embodiment of fig. 4 and 5, the letter a is replaced by the letter b.

Fig. 4 shows a side sectional view of an alternative power tool 10 b. In the exemplary embodiment shown in fig. 4, the power tool 10b is designed as a grinding machine, in particular as a triangular grinding machine. However, other configurations of the power tool 10b are also conceivable, which are considered to be expedient by the person skilled in the art. The power tool 10b is designed as an electrically driven power tool 10 b. The power tool 10b is battery-operated. Alternatively or additionally, it is conceivable that the power tool 10b can be driven in a cordless manner. The power tool 10b has a battery receptacle 40b, which is arranged in a housing 42b of the power tool 10 b. The housing 42b is in particular designed as a shell housing. The battery receptacle 40b is arranged, in particular, at least substantially in the handle 44b of the power tool 10 b. The battery receiving part 40b is provided for receiving a battery 46b for driving the power tool 10 b.

The power tool 10b has an oscillatably drivable tool receiver 12 b. The tool receiver 12b is configured as a grinding plate 38 b. The tool receptacle 12b is preferably provided for receiving a plug-in tool, in particular a sanding sheet, in a repeatedly detachable manner by an operator. Fig. 5 shows a plan view of the underside of the tool receiver 12 b. The power tool 10b also has a drive unit 14b for driving the tool receiver 12 b. The drive unit 14b has an electric motor 52b, which is provided to convert the electrical energy provided by the battery 46b into kinetic energy, in particular into rotational energy. The drive unit 14b has a drive shaft 16b for driving at least the tool receiving portion 12b, which has a drive axis 18b intersecting the tool receiving portion 12 b. The drive shaft 16b is formed, in particular, at least in part by an armature shaft 54b of the electric motor 52 b. Furthermore, the power tool 10b comprises a support unit 20b for movably supporting the tool receiver 12b about a support axis 22b of the support unit 20b, which support axis intersects the tool receiver 12 b. The bearing unit 20b is provided in particular for movably bearing the tool receiver 12b relative to the housing 42b of the power tool 10 b. The drive unit 14b is arranged behind the support unit 20b within the housing 42 b. The drive axis 18b is configured differently from the bearing axis 22 b. The bearing axis 22b and the drive axis 18b extend at least substantially spatially spaced apart from one another. The bearing axis 22b extends in particular only along at least one component of the bearing unit 20 b. The drive axis 18b extends in particular only along at least one component of the drive unit 14b, in particular along the drive shaft 16 b. The drive axis 18b extends at least substantially along the drive shaft 16b, in particular along an armature shaft 54b of the electric motor 52 b. The drive axis 18b extends at least substantially parallel offset relative to the bearing axis 22 b.

The bearing axis 22b intersects the tool receiver 12b offset from the drive axis 18 b. The bearing axis 22b intersects the tool receiver 12b at least substantially centrally. The bearing axis 22b and the drive axis 18a intersect the tool receiver 12b at two

intersection points

56b, 58b which are spaced apart from one another in space. The drive axis 18b intersects the tool receiver 12b, in particular, at an intersection point 56b, which lies on a circle 60b around an intersection point 58b between the bearing axis 22b and the tool receiver 12 b. The drive axis 18b intersects the tool receiver 12b at an intersection point 56b between a circle 60b about an intersection point 58b between the bearing axis 22b and the tool receiver 12b and a main direction of extension 62b of the machine tool 10 b. The drive axis 18b intersects the tool receiving portion 12b rearward of the support axis 22 b.

The bearing unit 20b has a bearing pin 24 extending along a bearing axis 22b, on which the tool receiver 12b is rotatably mounted about the bearing axis 22 b. The support tongues 24b are at least substantially cylindrical in shape. The support tongue 24b is in particular designed at least in a force-fitting manner with the housing 42b of the power tool 10 b. The support tongue 24b may be formed in particular integrally with the housing 42b of the power tool 10 b. The bearing axis 22b extends in particular at least substantially along a main direction of extension of the bearing pin 24 b.

The drive unit 14b has a rolling bearing 28b arranged eccentrically with respect to the drive axis 18b on the drive shaft 16 b. The rolling bearing 28b is in particular designed as a ball bearing. The rolling bearing 28b is provided for transmitting the movement from the drive shaft 16b to the tool receiver 12 b. The tool receiver 12b has two running

surfaces

30b, 32b, which are provided to convert a movement of the rolling bearing 28b into a pivoting movement 36b of the tool receiver 12b about the bearing axis 22 b. The working

surfaces

30b, 32b are in particular formed integrally with the tool holder 12 b. The running surfaces 30b, 32b extend in particular at least substantially parallel to one another. During rotation of the drive shaft 16b, the rolling bearing 28b describes an eccentric movement about the drive axis 18 b. A rolling bearing 28b arranged eccentrically to the drive axis 18b on the drive shaft 16b is provided for alternately loading the running

surfaces

30b, 32b with force during rotation of the drive shaft 16 b. The alternating loading of the working

surfaces

30b, 32b is provided for setting the tool receiver 12b into a pivoting movement 36b about the bearing axis 22 b.

Claims

1. A portable machine tool has

At least one tool receptacle (12 a; 12b) that can be driven in an oscillating manner,

-at least one drive unit (14 a; 14b) having at least one drive shaft (16 a; 16b) for driving at least the tool receiving part (12 a; 12b), the drive shaft having at least one drive axis (18 a; 18b) intersecting the tool receiving part (12 a; 12b), and

at least one bearing unit (20 a; 20b) for movably supporting the tool holder (12 a; 12b) about a bearing axis (22 a; 22b) of the bearing unit (20 a; 20b), which intersects the tool holder (12 a; 12b),

characterized in that the drive axis (18 a; 18b) is configured differently from the bearing axis (22 a; 22b), in that the drive unit (14 a; 14b) has a rolling bearing (28 a; 28b) arranged eccentrically to the drive axis (18 a; 18b) on the drive shaft (16 a; 16b), and in that the tool holder (12 a; 12b) has at least one running surface (30a, 32 a; 30b, 32b) which is provided for converting a movement of the rolling bearing (28 a; 28b) into an oscillating movement (36 a; 36b) of the tool holder (12 a; 12b) about the bearing axis (22 a; 22 b).

2. Machine tool according to claim 1, wherein the bearing axis (22 a; 22b) intersects the tool receptacle (12 a; 12b) offset from the drive axis (18 a; 18 b).

3. Machine tool according to claim 1 or 2, wherein the drive axis (18 a; 18b) extends offset parallel to the bearing axis (22 a; 22 b).

4. Machine tool according to claim 1 or 2, characterized in that the bearing axis (22 a; 22b) intersects the tool receiver (12 a; 12b) centrally.

5. The machine tool according to claim 1 or 2, wherein the bearing unit (20 a; 20b) has at least one bearing pin (24 a; 24b) which extends along the bearing axis (22 a; 22b), the tool holder (12 a; 12b) being fixed on the bearing pin in a rotatable manner about the bearing axis (22 a; 22 b).

6. Machine tool according to claim 1 or 2, wherein the bearing unit (20 a; 20b) has at least one radial bearing (26 a; 26b) which is provided for rotatably supporting the tool receiver (12 a; 12b) about the bearing axis (22 a; 22 b).

7. Machine tool according to claim 1 or 2, characterized in that the rolling bearing is provided for transmitting a movement from the drive shaft (16 a; 16b) to the tool receptacle (12 a; 12 b).

8. Machine tool according to claim 1 or 2, characterized in that the portable machine tool is a grinding machine.

9. A tool holder for a machine tool (10 a; 10b), according to one of claims 1 to 8, characterized in that at least one holder (34 a; 34b) for at least one radial bearing (26 a; 26b) is provided, which is provided for mounting the tool holder (12 a; 12b) in a rotatable manner about a bearing axis (22 a; 22b), and at least one running surface (30a, 32 a; 30b, 32b) is provided, which is provided for converting a movement of a rolling bearing (28 a; 28b) into a pivoting movement (36 a; 36b) of the tool holder (12 a; 12b) about the bearing axis (22 a; 22 b).

10. The tool receiving portion of claim 9, wherein the tool receiving portion is a grind plate.

11. A method for oscillatingly driving a tool receptacle (12 a; 12b) according to claim 9 or 10, characterized in that a movement of a rolling bearing (28 a; 28b) arranged eccentrically with respect to a drive axis (18 a; 18b) on a drive shaft (16 a; 16b) is converted into an oscillating movement (36 a; 36b) of the tool receptacle (12 a; 12b) about a bearing axis (22 a; 22b) different from the drive axis (18 a; 18 b).