MACHINE TOOL DRIVEN IN AN OSCILLATING MANNER

Abstract

An oscillatingly driven machine tool having a housing in which a motor with a motor shaft is received, on which an eccentric element is accommodated, with a spindle head, with a tool spindle that is rotatably mounted about its longitudinal axis in the spindle head, on which a coupling element is non-rotatably received, which cooperates with the eccentric element for generating a movement of the tool spindle which oscillates about its longitudinal axis such that, in addition to the oscillating movement, a differing, superimposed movement is introduced into the coupling element.

Claims

1. An oscillatingly driven machine tool comprising: a motor with a motor shaft; a housing in which the motor with the motor shaft is accommodated; an eccentric element; a spindle head; and a tool spindle rotatably mounted about a longitudinal axis in the spindle head on which a coupling element is non-rotatably received, which cooperates with the eccentric element for generating an oscillating movement of the tool spindle about its longitudinal axis such that, in addition to the oscillating movement, a differing superimposed movement is introduced into the coupling element.

2. The machine tool according to claim 1, wherein, in an area of its two ends, the tool spindle is rotatably mounted in the housing via two bearings and is mounted linearly movable perpendicular to the longitudinal axis.

3. The machine tool according to claim 1, wherein the coupling element is a lever which is fixed between the two bearings on the tool spindle.

4. The machine tool according to claim 3, wherein the coupling element is guided in a slotted guide via a guide element for generating the superimposed movement.

5. The machine tool according to claim 4, wherein the slotted guide is arranged and configured such that it is symmetrical with respect to a symmetry line extending through the longitudinal axis of the tool spindle between two reversal points of the coupling element.

6. The machine tool according to claim 1, wherein the slotted guide is interchangeable.

7. The machine tool according to claim 1, wherein a ball bearing is accommodated on the eccentric element, the ball bearing being held on an outer side in a fork-shaped coupling element.

8. The machine tool according to claim 4, wherein a threaded spindle is provided to move the guide element and the slotted guide between an engagement position, in which the guide element is guided in the slotted guide for generating the superimposed movement, and an inactive position, in which the guide element is disengaged from the slotted guide and a linear mobility is blocked.

9. The machine tool according to claim 4, further comprising a spring for bringing the guide element into engagement with differing slotted guides or with differing sections of a slotted guide to produce differing superimposed movements.

10. The machine tool according to claim 8, wherein the slotted guide is displaceable along an extension direction.

11. The machine tool according to claim 1, wherein the eccentric element is a ball head that is guided in an inner slotted guide in the coupling element.

12. The machine tool according to claim 1, wherein the tool spindle is secured against displacement in the axial direction.

13. The machine tool according to claim 1, wherein the tool spindle protrudes outwardly from the housing and is sealed in the region of its exit point from the housing with a membrane made of an elastomeric material.

14. The machine tool according to claim 1, wherein the slotted guide is formed such that the superimposed linear movement that is perpendicular to the longitudinal axis of the tool spindle has a maximum deflection when the coupling element is located in a middle position between the two reversal points of the oscillating movement.

15. The machine tool according to claim 1, wherein the tool spindle has at a free end a tool holder for fastening a tool, a sawing tool, or a grinding tool.

16. The machine tool according to claim 1, further comprising a controller that is coupled to the motor such that a control of a motor speed is carried out as a function of one or more predetermined parameters.

17. The machine tool according to claim 16, wherein a detector detects the rotational speed of the motor, and wherein the controller is designed to start the motor at a first rotational speed, and to increase the speed to a second speed, which is higher than the first speed when a load of the motor is detected.

18. The machine tool according to claim 16, wherein the controller is designed to lower the rotational speed of the motor when a decrease in the load is detected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0052] FIG. 1 is an overall perspective view of a machine tool according to an embodiment of the invention;

[0053] FIG. 2 is a partial section through the machine tool of FIG. 1, through the spindle head and through a part of the motor;

[0054] FIG. 3 is a section through the machine tool of FIG. 2 along the line III-III;

[0055] FIG. 4 is a partially cutaway perspective view, in which in particular, the coupling element with the ball bearing guided therein and the guide element as per the slotted guide are visible;

[0056] FIG. 5 is an enlarged view of FIG. 4, which is further cut free to make the oscillating drive more visible;

[0057] FIG. 6 is a view of the coupling element of FIG. 5 as seen from the fork-shaped seat for the ball bearing, together with the associated slotted guide;

[0058] FIG. 7 is an illustration of the coupling element together with the associated slotted guide, wherein in addition, the ball bearing can be seen together with the eccentric element received therein;

[0059] FIG. 8 is an illustration of an alternative embodiment of the invention, wherein the eccentric element is formed at its end as a ball head, which is guided in an inner slotted guide at the end of the coupling element;

[0060] FIG. 9 is the coupling element according to FIG. 8, but without the eccentric head;

[0061] FIG. 10 is an exemplary representation of a sawing tool, which can be mounted on the outer end of the tool spindle;

[0062] FIG. 11 is a simplified circuit diagram to illustrate the idling reduction of the engine;

[0063] FIG. 12 is a schematic representation in which the symmetrical arrangement of the slotted guide is shown with respect to a line of symmetry between the two reversal points of the coupling element;

[0064] FIG. 13 is a further modification of a machine tool according to the invention, wherein here only a modified slotted guide is shown in a perspective view;

[0065] FIG. 14 is a section through a further modification of a machine tool according to the invention in the region of the fork;

[0066] FIG. 15 is a perspective view of the associated slotted guides from above; and

[0067] FIG. 16 is a perspective view of the associated slotted guides from below.

DETAILED DESCRIPTION

[0068] FIG. 1 shows a machine tool according to the invention in the form of a hand tool, which is designated overall by the numeral 10. The machine tool 10 has an elongated housing 12 which can be gripped by one hand and at the top of which a switch 16 is provided for switching on and off.

[0069] At the front end of the housing 12, a spindle head 20 is integrally formed, from which a tool spindle 22 projects downwards with a free end. At the rear end facing away from the spindle head 20, a replaceable battery pack 14 is provided to power the machine. It is understood that, of course, a networked design could be used instead.

[0070] On the left side, an adjusting wheel 18 is additionally recognizable, which is designed to adjust the maximum speed of the drive motor.

[0071] The detailed structure of the machine tool 10 will now be described with reference to the following figures.

[0072] FIG. 2 shows a longitudinal section through the outer end of the machine 10.

[0073] In the housing 12, a motor 26 is accommodated, on the motor shaft 28 of which at the outer end 33 an eccentric element in the form of an eccentric pin with a hollow cylindrical extension 32 formed thereon is attached via a press fit. The motor shaft 28 is mounted with the outer periphery of the extension 32 in a ball bearing.

[0074] In the spindle head 20, the tool spindle 22 is held with its longitudinal axis 23 at right angles to the longitudinal axis 29 of the motor shaft. The tool spindle is rotatably mounted in the region of its two ends by means of two bearings 34, 36. In addition, the tool spindle 22 is movably mounted in a direction perpendicular to its longitudinal axis 23 and parallel to the longitudinal axis 29 of the motor shaft 28. For this purpose, one of the bearings 34 is held at the inner end of the tool spindle 22 in a bearing block 38 which is mounted by means of two axial needle bearings 41, 42 and two linear guides and is slidable in a direction parallel to the longitudinal axis 29 of the motor shaft 28. In a corresponding manner, the other bearing, designed as a needle bearing 36, is held in a bearing block 40 which is supported by two axial needle bearings 43, 44 and two linear guides and is movable in the direction perpendicular to the longitudinal axis 23 of the tool spindle and parallel to the longitudinal axis 29 of the motor shaft 28.

[0075] The tool spindle 22 can thus be rotationally oscillatingly driven about its longitudinal axis 23 (see double arrow 25) and additionally moved in the direction perpendicular to its longitudinal axis 23 and parallel to the longitudinal axis 29 of the motor shaft 28 (see double arrow 27).

[0076] To generate the rotational oscillating and superimposed linear movement, a coupling element 46 in the form of a lever is held rotationally fixed with one end on the tool spindle 22 between the two bearings 34, 36 by means of a press fit.

[0077] The coupling element 46, the shape of which is shown in more detail in particular in FIGS. 4 and 5, has at one end a cylindrical opening 54 (FIGS. 4, 5) which allows for connection to the tool spindle 22 by a press fit. The opposite second end is designed in the form of a fork 56. On one side of this fork (underside), this fork 56 is extended downwards and, according to FIG. 3, has a U-shaped cross-section. On the eccentric 33, a ball bearing 48 is held, which is accommodated in a seat surface 60 of an inner side of the fork 56.

[0078] Below the fork 56, a block 51 is held on the housing 12 with a slotted guide 52, in which a guide element 50 in the form of a pin engages, said pin protruding from the lower end of the fork 56 downwards.

[0079] If the eccentric 33 is driven by the motor shaft 28, a rotationally oscillating movement of the tool spindle 22 about its longitudinal axis 23 is produced on the one hand via the ball bearing 48 and the coupling element 46 (see double arrow 25). On the other hand, in the slotted guide 52, a superimposed oscillating linear movement (double arrow 27) is generated on the tool spindle 22, perpendicular to its longitudinal axis 23 and parallel to the longitudinal axis 29 of the motor shaft 28, by the engagement of the guide element 50 which is fixedly connected to the fork 56. Due to the arrangement and shape of the slotted guide 52, the trajectory of the superimposed oscillating linear motion can be influenced.

[0080] According to a preferred embodiment of the invention, the slotted guide 52 is arranged and designed such that it is symmetrical with respect to a line of symmetry 76 extending through the longitudinal axis 23 of the tool spindle 22 between the two reversal points 74, 75 of the coupling element 46 (see FIG. 12). In FIG. 12, the angle between the two reversal points (which is between 0.5 and 7) is shown clearly exaggerated for better visibility.

[0081] In this case, at the same distance to the respective reversal point 74, 75 of the oscillatory motion, the linear movement generated by the slotted guide 52 has the same stroke on both sides, respectively.

[0082] Such a configuration is advantageous if the machine tool is to be used to drive a sawing tool.

[0083] For this purpose, preferably the slotted guide 52 is further formed such that the linear movement which is superimposed perpendicular to the longitudinal axis 23 of the tool spindle 22 has a maximum deflection when the coupling element 46 is located in a middle position between its two reversal points 74, 75.

[0084] It has been found that such a configuration is particularly suitable in order to produce very good work progress in sawing work with minimal feed force.

[0085] FIG. 10 shows an exemplary tool 64 in plan view, which can be used as a sawing tool. It has a saw-toothed cutting edge 68 which runs concentric to a mounting opening 66 for fixing the tool 64 on the tool holder 24 on the outer end of the tool spindle 22.

[0086] It is understood that the shape of the mounting opening 66, which is shown here in a polygonal shape only by way of example, is adapted in a suitable manner to the shape of the associated seat 24 on the tool spindle 22. In the illustrated embodiment, a fastener is additionally used for attachment of the tool 64, which fastener engages through the mounting opening 66 of the tool 64 and is fixed in the tool spindle to guarantee a positive and/or non-positive connection. However, as the details of such attachment are known, a closer description is omitted at this point.

[0087] As indicated by way of example in FIG. 5 by a double arrow 58, it is possible, for example, by a movement of the block 51 in which the slotted guide 52 is formed, to displace the slotted guide 52 between the engagement position shown in FIG. 5, in which the guide element 50 engages in the slotted guide 52, and an inactive position.

[0088] In the inactive position, the block 51 is moved so far away from the guide element 50 that the guide element 50 is no longer engaged in the slotted guide 52. In this position, therefore, only the rotational oscillating movement is transferred to the tool spindle 22, but no additional linear motion.

[0089] Such a movement can be generated, for example, by replacing the mounting screw 59 visible in FIG. 5 with a threaded spindle that meshes with a thread in the block 51 and thus allows an adjustment in the direction of the double arrow 58. In this case, a block is provided to block the linear mobility of the tool spindle in the inactive position of the slotted guide, so that in this case the tool spindle is only rotationally oscillatingly driven and is movable.

[0090] FIGS. 8 and 9 show a modified embodiment of the invention, in which instead of the slotted guide 52, which cooperates with the guide element 50, a connection directly between the eccentric and the coupling element in the fork is provided.

[0091] For this purpose, the eccentric 30a is formed at its outer end as a ball head, which engages in an inner slotted guide 62 (see FIG. 9) at the end of the coupling element 46a in the area of the fork 56a. Due to the shape of the inner slotted guide 62 in connection with the ball head 30a of the eccentric, the movement is fixed. The movement curve can be adjusted by the design of the inner slotted guide 52.

[0092] As can be seen from FIG. 2, the tool spindle 22 is sealed at its outer end by a membrane 53 made from an elastomeric material, since the tool spindle 22 also moves in an oscillating linear manner.

[0093] In order to support the conducting of sawing work, the machine tool 10 is preferably additionally equipped with a so-called idling reduction.

[0094] A central controller 70, which is shown schematically in FIG. 11 and which cooperates with the motor 26, is designed such that at the beginning of a saw cut, the tool 64 is operated at a low speed n.sub.1, whereby the tool 64 can be guided very well. If the controller 70 coupled to the motor 26 detects that the motor 26 is loaded, the speed is slowly increased to a higher speed n.sub.2 until, where appropriate, a pre-set maximum speed is reached.

[0095] This allows for very fast work progress to be achieved without control of the cut being lost, since the saw blade is guided in the already produced cut. If the load on the machine declines, the speed is again decreased until finally the lower level n.sub.1 is reached again.

[0096] FIG. 13 describes a further modification of a machine tool according to the invention generally designated by 10b. Shown is only a block 51b with a slotted guide 52b with a middle region 74 and a first end region 76 and a second end region 78. The block 51b is displaceable in the direction of its longitudinal extent, such as indicated by a double arrow 79.

[0097] As a result, either the middle region 74 or one of the two end regions 76, 78 can be brought into engagement with the associated guide element 50 to create differing superimposed movements. If desired, the middle region 74 can also be used to generate no superimposed movement.

[0098] FIGS. 14 to 16 show a further modification of the inventive machine tool, which is designated overall by 10c. From the section in FIG. 14, it can be seen that in the lower end of the fork 56c, a guide element 50c in the form of a tappet is held axially displaceable against the force of a spring element 80. The guide element 50c may be brought into engagement with either an upper slotted guide 82 or with a lower slotted guide 84 on the underside of the block 51c. This results in differing superimposed movements, depending on whether the upper slotted guide 82 or the lower slotted guide 84 is engaged.

[0099] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.