Patent Application
20090249626
The present invention relates to a method for the machining of workpieces, in particular of rotationally symmetrical workpieces, e.g. vehicle wheel rims.
It is the object of the invention to provide a method and an apparatus for the machining of workpieces with which an improved influencing of different geometries of the workpiece is possible during the machining process.
This object is satisfied by the features of the independent claims.
Using the method in accordance with the invention, the workpiece is simultaneously rotated about its own central vertical axis by a first drive motor; its central axis is moved along an orbital movement along a closed orbit about a rotating vertical axis by a second drive motor; and this vertical axis is rotated about a stationary vertical axis of rotation with the help of a third drive motor. Due to the connection of three separate drive motors, they can be controlled separately and a clear improvement and standardization of the material removal can be achieved. Since the workpiece is not only moved about its own central vertical axis, but also about an orbital path, which is in turn rotated about a stationary vertical axis of rotation, a best possible standardization of the grinding result can be achieved. Much improved results were able to be achieved in contrast to grinding processes in which the workpiece is admittedly rotated about three axes of rotation parallel to one another, but not about its own central axis.
Using the apparatus in accordance with the invention, the orbital movement and the rotational movement of the workpiece is effected with the help of two separate drive motors, whereby these two drives can be regulated independently separately from one another and are no longer fixedly coupled. Much improved machining results can hereby be achieved and a considerable improvement and standardization of the material removal can be achieved at the rim surface, from the inside to the outside, and an ideal throughflow behavior as well as a uniform material removal can be achieved from the center of the workpiece up to its outer periphery.
Advantageous embodiments of the invention are described in the description, in the drawing and in the dependent claims.
In accordance with a first advantageous embodiment, a plurality of workpieces can be dipped into the container and can be moved relative to the container, with all the workpieces being rotated about their own central vertical axes, about the rotating vertical axis and about the stationary vertical axis of rotation. In this process, the advantage results that possible machining shadows are minimized since each workpiece is also rotated about its own central axis and thus no part of the workpiece circulates on a circular path on which the part is always directed to the center of this circular path.
In accordance with a further advantageous embodiment, the workpiece can be moved in a direction of rotation along the closed orbit, with the workpiece being moved about its own central axis in the direction of rotation opposite thereto. Very good results have been achieved, in particular by variation of the respective speeds of rotation, by such an opposite sense of direction of the orbital movement, on the one hand, and of the rotational movement, on the other hand. It is therefore advantageous if the speed of the first drive motor is varied independently of the speed of the second drive motor.
In accordance with a further advantageous embodiment, none of the drive motors is exposed to a rotational or orbital movement. This contributes to a long service life of the apparatus since the two drive motors only have to be exposed to the oscillation movement which, however, takes place at a comparatively low speed.
In accordance with a further advantageous embodiment, a wobble movement can additionally be applied to the workpiece to increase the relative movement between the processing means and the workpiece even further.
Good results have also been able to be achieved in that the maximum speed of the rotational movement and of the orbital movement is selected to be lower than approximately 150 r.p.m.
In accordance with an advantageous embodiment of the apparatus, the two drive motors are mounted on a component which is either stationary, for example when the processing means container is oscillated, or which can be oscillated by an oscillation device. The advantage likewise results in this embodiment that the two electric motors are not subject to any fast rotational movements, but are rather only subject to a comparatively slow oscillation movement.
In accordance with a further advantageous embodiment, the orbital drive has a component which is rotatably driven by a drive motor and at which the chuck is fastened eccentrically and rotatably. In this manner, the chuck which circulates about the orbital track can be rotated about its own axis using a drive motor which does not itself circulate along the orbital track, but rather remains stationary—in comparison with the movement of the workpiece. It can be advantageous in this respect when the rotation device has a shaft which is rotatably driven by the other drive motor, which extends through the component and which is in rotational communication with the chuck. A cost-effective solution is hereby created which manages with only a few components and nevertheless ensures the desired decoupling of the different movements.
In accordance with a further advantageous embodiment, a third drive motor can be provided with which the vertical axis is rotatable about a stationary vertical axis of rotation so that the workpiece rotates about its own central axis, on the one hand, and the workpiece circulates on an orbital track and rotates about the stationary vertical axis of rotation, on the other hand.
In accordance with a further advantageous embodiment, the rotation device can have a plurality of chucks which can be set into rotation about their own central axes either via a common transmission, for example a planetary transmission, or via a respective drive of their own. In this embodiment, the chucks are arranged coaxially to one another and are rotated about their own axes of rotation, on the one hand, about the rotating axis of rotation, on the other hand, and finally also about the stationary axis of rotation, whereby best machining results are achieved. Even if in the above the movement of the workpiece is preferably described relative to the processing means container, it is always assumed that it generally of no significance for the invention whether the described movements are achieved by movement of the workpiece or, alternatively, by movement of the container. In the embodiment described, however, it is not the container which is moved, but exclusively the rim since this requires a lower effort with respect to the apparatus and to the construction.
It must additionally be noted that the method in accordance with the invention is generally suitable for all workpieces and in particular also for rotationally symmetrical workpieces. All type of rims or wheels can be considered as rims, i.e. rims for automobiles, trucks or motorcycles in all sizes and variations. The machining can be a deburring, descaling, rounding, grinding, polishing or the like.
The present invention will be described in the following purely by way of example with reference to an advantageous embodiment and to the enclosed drawing.
There are shown:
The machining apparatus shown in
An agitation element 14 is provided at the base of the container 12 which has a plurality of paddles which extend parallel to the base and which are rotatingly driven about a vertical axis of rotation D via a drive 16 which is disposed beneath the container base.
Furthermore, a machine stand 18 is arranged on the base frame 10 and a transverse member 20 is fastened thereto displaceably in the vertical direction, that is along the double arrow X. The vertical movement is in this respect effected via a drive 22 which is not shown in any more detail and which effects, in conjunction with a lift cylinder 24, a raising and a lowering of the transverse member 20. In this respect, the transverse member is raised or lowered along the axis A in the direction of the double arrow X. In the position shown in
At the outer end of the transverse member 20, a chuck 28 is mounted at the lower end of a shaft 27 guided in a shaft 26, said chuck serving for the fastening of a workpiece, for example of a rim F. In this respect, the shaft 27 is fastened to a transmission 30 which is shown in enlarged form in
As
As
To achieve a rotational movement of the chuck 28 about the axis B independently of the orbital movement effected by the drive motor 32, a further drive motor 56 is provided at the outer end of the transverse member 20, said further drive motor driving a vertical shaft 58 which circulates about the axis of rotation C and which extends through the hollow shaft 42. The shaft 58 thus extends along the axis C through the upper half and the lower half of the turntable 44 and is connected at its lower end to a gear 60 which meshes with a further gear 62 which is in communication with the shaft 27 rotatably journaled in the shaft 26. In this manner, the chuck 28 can be rotated about its own central vertical axis B with the help of the second drive motor 56 independently of the orbital movement and independently of a control of the first drive motor 32. The drive 22 thus effects the oscillation movement of the rim F along the axis A in the direction of the double arrow X and the drive motor 32 effects the orbital movement about the axis C, while the drive motor 56 effects the rotational movement of the rim F about its central axis B.
As
All the drives 16, 22, 32 and 56 and also a drive 70 (
In the apparatus described above, the shaft 26 has an offset of approximately 100 mm to the axis of rotation C. An offset from approximately 80 to approximately 150 mm can be advantageous.
In a method in accordance with the invention, a workpiece, for example, a vehicle wheel rim is dipped into the container filled with processing means, is moved along a closed orbit and is additionally rotated about its own central axis, with the center of the closed orbit being rotated about a stationary vertical axis. It can be advantageous in this respect if the workpiece is moved in a direction of rotation along the closed orbit and is moved about its own central axis in the opposite direction of rotation. The drive 32 can be controlled, for example, such that the workpiece F is moved clockwise along an orbital track within the container 12, while it rotates counter-clockwise about its own axis of symmetry B.
In practice, very good results have been achieved with the following operating parameters for grinding and polishing:
When work takes place with opposite directions of rotation, the effective drive speed can be calculated from the difference of the orbital speed and the spindle speed.
The orbital drive 32 can preferably be regulated between approximately 30 and 130 r.p.m., while the spindle drive 56 can preferably be regulated from approximately 40 to 200 r.p.m.
Additional oscillation movements in the vertical direction have also proved to be advantageous during the machining.
The maximum stroke length in the vertical direction can amount to approximately 350 mm and can be limited to a maximum frequency of approximately 60 strokes a minute.
In the embodiment shown in
In the embodiment shown in
In all the embodiments shown, a plurality of chucks can be provided in parallel and eccentrically about the rotating axis of rotation C. For example, the chucks can each be rotated about their own central axes with the help of a planetary transmission and with the help of a common drive motor. Alternatively, a separate drive motor can be provided for each chuck to be able to set the speed of the respective workpiece individually for its own rotation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 017 841.1 | Apr 2008 | DE | national |
