WO2015193054A1

WO2015193054A1 - Power tool

Info

Publication number: WO2015193054A1
Application number: PCT/EP2015/061212
Authority: WO
Inventors: Ralf Seebauer
Original assignee: C. & E. Fein Gmbh
Priority date: 2014-06-16
Filing date: 2015-05-21
Publication date: 2015-12-23
Also published as: DE102014108401A1

Abstract

The invention relates to a motor-driven power tool having a drive motor (16), the motor shaft (18) of which is driven in a rotating manner, comprising a tool driveshaft (24) which is driven in an oscillating manner or in a rotating manner about the longitudinal axis (25) of the tool driveshaft and comprising a coupling gear (20) for converting the rotational movement of the motor shaft (18) into a driving movement of the tool driveshaft (24). Furthermore, a coupling (22) with an elastic element (52) is provided for compensating for a relative movement or an angular offset between the motor shaft (18) and the tool driveshaft (24).

Description

machine tool

The invention relates to a motor-driven machine tool with a drive motor whose motor shaft is driven in rotation, with a tool drive shaft which is driven to rotate or oscillate about its longitudinal axis, and with a coupling drive for converting the rotational movement of the motor shaft into a drive movement of the tool drive shaft, and with a coupling between the motor shaft and the tool drive shaft.

Such a machine tool is known from JP-62074564 A. This is an angle grinder in which a coupling with two universal joints and a sliding joint is provided between the motor shaft and the tool drive shaft. In combination with a damping element on the housing should In this case, a vibration reduction can be achieved. The known arrangement is relatively complicated and suitable only for angle grinder.

In addition, more and more machines with oscillating drive movement of the tool drive shaft are in use in recent years, the tool drive shaft can be driven to oscillate about its longitudinal axis. Such oscillating machine tools are used in a variety of ways for grinding, cutting, sawing, etc.

Especially with oscillating driven machine tools, but also in certain machine tools with rotating driven tool drive shaft, such as angle grinders, there is the problem that vibrations may occur, which adversely affect the life of the machine and are perceived by the user to be detrimental.

If the motor shafts and the tool drive shaft are not aligned concentrically or axially parallel to each other, so unilateral stresses of the bearings, and it may possibly over time come to overloads, premature defects or failures.

In oscillating driven machine tools, the rotating drive movement of the motor shaft is converted by a suitable coupling drive in an oscillating drive movement of the tool drive shaft. This can lead to a relative movement between the drive motor and the coupling drive by a vibration decoupling or damping. Also in this case, a concentric and axially parallel alignment of the motor shaft and tool drive shaft is thus no longer possible.

From EP 2 139 647 B1 an oscillatingly driven machine tool according to the preamble of claim 1 is known, in which between the drive shaft and the motor drive shaft, a length compensation approximately using a star-shaped profile is provided, which engages in a bore with a corresponding profiling.

With such an embodiment, however, only a length compensation in the field of the drive train is made possible.

Against this background, the present invention seeks to provide a machine tool that reduces oscillations and minimizes the burden on the storage and the coupling drive between the motor shaft and the tool drive shaft.

This object is achieved in a machine tool according to the aforementioned type in that the coupling has an elastic element.

The object of the invention is achieved in this way.

In this way, a damping effect is integrated directly into the clutch. The effect of tolerance differences is minimized and effective damping of oscillations is ensured, especially when using oscillation drives

According to the risk of vibrations is significantly reduced by the elastic element of the coupling. In addition, the risk of overloading the bearings and the material in the drive train is significantly reduced. In the case of vibration-decoupled machine tools with an oscillatingly driven tool drive shaft, the risk of overloading of the bearing points is markedly reduced and, at the same time, the vibration load is limited.

In an advantageous embodiment of the invention, the coupling comprises a coupling shaft which is coupled on a drive shaft to the motor shaft via a first articulated connection, and which is connected on a driven side via a second articulated connection. is coupled to the coupling drive, wherein between the drive side and the output side at least one sliding joint connection is provided.

With such an embodiment, angular errors and changes in position between the motor shaft and the tool drive shaft or the interposed coupling drive can be compensated. A design-related offset or angle error between the motor axis with respect to a concentric or axis-parallel alignment with the tool drive shaft can be tolerated.

Here, the first hinge connection may comprise, for example, a first ball head which is guided on an inner surface of the coupling shaft and which drives the coupling shaft via a drive pin, wherein the second hinge connection comprises a second guided on an inner surface of the coupling shaft ball head, of the coupling shaft is driven by a driven pin.

According to one embodiment of this embodiment, the coupling shaft is designed as a hollow shaft.

The elastic member may further be formed as a sleeve which is received in the coupling shaft.

Furthermore, the sleeve may be enclosed by an inner surface of the coupling shaft and the first and second ball head may be guided on the inner surface of the sleeve.

By these features, an effective damping is ensured directly by the elastic element and a simple construction.

The elastic element may consist of a rubber material, a thermoplastic material, a felt material, a foam material, in particular of a PU foam. On the one hand, this ensures a sufficiently long lasting On the other hand, felt can serve as a lubricant carrier and reduce wear.

Preferably, the drive bolt and the driven bolt are each guided with their ends in slots in a wall of the coupling shaft longitudinally displaceable.

With these measures, a simple embodiment of the coupling is made possible, which compensates both an angular offset and a positional offset between the motor shaft and tool drive shaft or between the motor shaft and coupling gear.

According to one embodiment of this embodiment, the slots in the wall of the coupling shaft slots are assigned in the elastic element, which are formed narrower than the slots in the wall.

Thus, the bolts can be transmitted with their ends normally the torque on the edges of the slots in the elastic element, whereby additional damping is given.

Only in the case of a load of the drive on the rated torque beyond the bolts strike with their ends to the edges of the slots in the wall of the clutch shaft. Thus, significantly higher torques can be transmitted, but then unattenuated. There is no risk of overloading or damaging the elastic element.

Preferably, in this case, the slots in the wall of the coupling shaft 0.5 to 2 millimeters, preferably 0.8 to 1, 5 millimeters, more preferably about 1 millimeter wider than the slots in the elastic element.

This allows a particularly favorable coordination between damping and sufficiently high torque transmission. According to a further embodiment of the invention, a housing is provided with a motor housing portion for receiving the drive motor and with a gear housing portion for receiving the tool drive shaft and preferably the coupling drive, wherein the motor housing portion and the gear housing portion relative to each other are movable, preferably yielding, interconnected ,

Further, the elastic element for vibration decoupling between the coupling drive and the drive motor may be formed.

If relative movements between the tool drive shaft and the drive motor are possible, fewer vibrations are transmitted to the drive motor. If the machine tool is held by hand in the area of the motor housing, significantly fewer vibrations are transmitted to the user. The reduction of vibrations on the drive motor and the associated accumulator also has an advantageous effect on the service life.

Compensating movements between the drive motor and the tool drive shaft or coupling drive or between the gear housing and the motor housing are collected by the coupling.

According to a further embodiment of the invention, the coupling drive on an eccentric coupling drive for implementing a rotary drive movement of the motor shaft in an oscillating movement of the tool drive shaft about its longitudinal axis.

In an alternative manner of the invention, the tool drive shaft is driven in rotation, wherein the machine is designed as an angle grinder, wherein the coupling drive is designed as an angular gear, in particular as a bevel gear. Even with such an embodiment, the advantages of the invention result by reducing the bearing load and the possible compensation of vibrations that may occur during operation.

It is understood that the above-mentioned and the features of the invention to be explained below not only in the combination, but also in other combinations or alone, without departing from the scope of the invention.

Further features and advantages of the invention will become apparent from the description of preferred embodiments with reference to the drawings. Show it:

Fig. 1 is a partial longitudinal section of a machine tool according to the invention with an oscillating driven tool drive shaft;

FIG. 2 shows a first perspective view of the coupling according to FIG. 1 in an enlarged illustration; FIG.

FIG. 3 shows a second perspective view of the coupling according to FIG. 1 in an enlarged view; FIG.

Fig. 4 is an enlarged longitudinal section through the coupling according to FIGS. 2 and 3 and

Fig. 5 is a simplified schematic representation of an alternative embodiment of the invention as an angle grinder.

In Fig. 1, a first embodiment of a machine tool according to the invention is generally designated by the numeral 10. It is an oscillatingly driven machine tool 10 with a motor housing 12, in which a drive motor 14 is received, and with a transmission housing 13, in which a Tool drive shaft 24 is received. A rotational movement of the motor shaft 18 is converted by a coupling 22 and an associated coupling drive 20 in an oscillating driven drive movement of the tool drive shaft 24 about its longitudinal axis 25.

At the outer end of the tool drive shaft 24, which projects outwardly from the gear housing 13, a tool holder 43 is provided, to which an associated tool, e.g. a grinding, cutting or sawing tool, fixed with a securing element 16 and (not shown) by means of a quick-clamping device with the aid of a clamping lever 26 can be clamped.

The tool drive shaft 24 is supported by means of two bearings 38, 40 on the transmission housing 13.

The drive motor 14 drives via its motor shaft 18 a coupling 22, with a first articulated connection 44 on the side of the motor shaft 18 and with a second articulated connection 46 on the output side.

The second articulated connection 46 is connected to an eccentric shaft 34, which is part of a coupling drive 20 in the form of an eccentric coupling drive, which drives the tool drive shaft 24 in an oscillating manner.

On an eccentric at the end of the eccentric shaft 34, an eccentric bearing 36 is held. At the eccentric bearing 36 engages an eccentric lever with a U-shaped fork (not shown), the other end is rotatably connected to the tool drive shaft 24.

In this way, an eccentric movement of the eccentric bearing 36 is converted into an oscillating movement of the tool drive shaft 24 about its longitudinal axis 25. The eccentric coupling drive 20 and the tool drive shaft 24 are decoupled from the drive motor 14 in terms of vibration. For this purpose, the motor housing 12 and the gear housing 13 are yieldingly connected to each other.

In this way, the transmission of vibrations from the tool drive shaft 24 and the coupling drive 20 to the drive motor 14 is reduced. A user holding the machine tool 10 on the motor housing 12 experiences substantially less vibration.

The closer embodiment of the provided between the coupling drive 20 and the drive motor 14 clutch 22 is shown in FIGS. 2 to 4.

The coupling 22 has a hollow cylindrical coupling shaft 42 which is driven via a first articulation 44 of the motor shaft 18 and which drives the eccentric shaft 34 via a second articulated connection 46.

In the coupling shaft 42, an elastic member 52 is held in the form of a sleeve, which consists for example of PU foam.

The first articulated connection 44 has a first ball head 45, which is rigidly and non-rotatably connected to the end of the motor shaft 18. The first ball head 45 is penetrated by a drive pin 54, which are guided in associated slots 58 in the lateral surface of the coupling shaft 42 and the elastic member 52. The first ball head 45 is guided on the inner surface of the elastic member 52.

The second hinge 46 has a second ball head 47 which is connected to the tool drive shaft 24 and which is also guided on the inner surface of the elastic member 52. The second ball head 47 is penetrated by a driven bolt 56, whose two ends are guided longitudinally displaceably in associated slots 60 in the lateral surface of the coupling shaft 42 and the elastic member 52. The second ball head 47 is rigidly and non-rotatably connected to the eccentric shaft 34. The coupling 22 allows an angular offset and a change in position between the motor shaft 18 and the eccentric shaft 34. Furthermore, the coupling 22 as a result of the elastic member 52 has an integrated damping.

Thus, should a precise alignment between the eccentric shaft 34 and the motor shaft 18 change as a result of vibrations, for example, the coupling 22 enables flexible compensation. Likewise, it is conceivable, the eccentric shaft 34 and the motor shaft 18 angularly or positionally offset from each other to order.

Preferably, the slots 58, 60 in the lateral surface of the coupling shaft 42 are slightly wider than the associated slots in the elastic member 52, preferably by an amount of about 1 millimeter. In this way, additional damping in the direction of the torque transmission can be effected, if normally the torque transmission takes place only via the slots of the elastic element. Only with heavy load on the rated torque beyond the torque transmission takes place by abutment of the bolt ends at the edges of the slots 58, 60 in the lateral surface of the coupling shaft 42. Thus, in the event of an overload torque transmission is ensured while damage to the elastic member 52 can be avoided.

5, a modification of the machine tool according to the invention is shown and indicated generally at 10a. Corresponding reference numerals are used for corresponding parts, which are partially supplemented by "a".

This is an embodiment of the machine tool in the form of an angle grinder with a gear head, a side handle for holding the machine, and with a conventional protective hood, which serves as a burst protection for a tool in the form of a grinding or cutting disc.

As can be seen from FIG. 5, in this case the coupling drive 20a received in the gear head 58 is constructed as a bevel gear angle gear. The mounted by means of two bearings 38, 40 tool drive shaft 24 is thus driven in rotation. The engine le 18 of the drive motor 14 drives a mounted by means of two bearings 28, 30 intermediate shaft 34a via a coupling 22 according to the previously described with reference to FIGS. 2 to 4 embodiment. On the intermediate shaft 34a is a pinion gear in the form of a bevel gear that drives an associated driven gear in the form of a bevel gear on the tool drive shaft 24.

Also in this embodiment, the additional coupling 22 serves to reduce vibrations that may occur during operation of the angle grinder.

In addition, the clutch 22 makes it possible to use an angular or positional offset between the motor shaft 18 and the intermediate shaft 34a. Also, the coupling drive 20a could be formed with the bevel gear in an angle deviating from 90 °.

The clutch 22 allows positional and angular changes between the drive shaft 24 and the motor shaft 18 during operation. It is therefore useful to provide a certain flexibility in the storage of the coupling drive 20 or 20a or the tool drive shaft 24 or motor shaft 18 to allow compensating movements that may arise during operation. It is sufficient for this purpose to provide a certain flexibility between the motor housing 12 and the gear housing 13. Advantageously, however, additional damping elements for vibration damping in the transition region between the motor housing 12 and the transmission housing 13 may be provided.

Due to the elastic configuration of the clutch 22, a damping function is integrated into the clutch itself. In addition, tolerance differences are compensated to a certain extent.

Claims

claims

Motor-driven machine tool having a drive motor (14) whose motor shaft (18) is driven in rotation, with a tool drive shaft (24) which is driven to rotate or oscillate about its longitudinal axis (25), and with a coupling drive (20) for converting the rotational movement the motor shaft (18) in a drive movement of the tool drive shaft (24), and with a coupling (22) between the motor shaft (18) and the tool drive shaft (24), characterized in that the coupling (22) has an elastic element (52).

Machine tool according to claim 1, characterized in that the coupling (22) comprises a coupling shaft (42) which is coupled on a drive side with the motor shaft (18) via a first articulated connection (44), and on a driven side via a second articulated connection (46) is coupled to the coupling drive (20), and that between the drive side and the output side at least one sliding joint connection (48, 54, 56, 60) is provided.

Machine tool according to claim 1 or 2, characterized in that the first hinge connection (44) comprises a first ball head (45) which is guided on the coupling shaft (42) and which drives the coupling shaft (42) via a drive pin (54), and in that the second articulated connection (46) comprises a second ball head (47) guided on the coupling shaft (42), which is driven by the coupling shaft (42) via an output stud (56).

Machine tool according to claim 3, characterized in that the coupling shaft (42) is designed as a hollow shaft.

Machine tool according to one of claims 2 to 4, characterized in that the elastic element (52) as a sleeve (52) is formed, which is received in the coupling shaft (42).

6. Machine tool according to claim 5, characterized in that the sleeve (52) from the inner surface of the coupling shaft (42) is enclosed, and that the first and second ball head (45, 47) on the inner surface of the sleeve (52) are guided.

7. Machine tool according to one of the preceding claims, characterized in that the elastic element (52) consists of a rubber material, a thermoplastic material, of a felt material, a foam material, preferably of a PU foam.

8. Machine tool according to one of claims 3 to 7, characterized in that the bolts (54, 56) in slots (58, 60) in a wall of the coupling shaft (42) are guided longitudinally displaceable.

9. Machine tool according to claim 8, characterized in that the slots (58, 60) in the wall of the coupling shaft (42) slots in the elastic member (52) are associated, which are formed narrower than the slots (58, 60) in the Wall.

10. Machine tool according to claim 9, characterized in that the slots (58, 60) in the wall 0.5 to 2 millimeters, preferably 0.8 to 1, 5 millimeters, more preferably about 1 millimeter wider than the slots in the elastic Element (52).

1 1. Machine tool according to one of the preceding claims, characterized in that a housing (12) is provided, with a motor housing portion (12) for receiving the drive motor (14), and with a gear housing portion (13) for receiving the tool drive shaft (24) and preferably of the Coupling drive (20, 20a), wherein the motor housing portion (12) and the gear housing portion (13) are movable relative to each other, preferably compliant, interconnected.

12. Machine tool according to claim 1 1, characterized in that the elastic element (52) for vibration decoupling between the coupling drive (20, 20a) and the drive motor (14) is formed.

13. Machine tool according to one of the preceding claims, characterized in that the coupling drive (20) has an eccentric coupling drive (32) for implementing a rotary drive movement of the motor shaft (18) in an oscillating movement of the tool drive shaft (24) about its longitudinal axis (25).

14. Machine tool according to one of claims 1 to 12, characterized in that the tool drive shaft (24) is driven in rotation, and that the machine is designed as angle grinder (10a), wherein the coupling drive (20a) formed as an angle gear, in particular as a bevel gear is.