Patent Application
20230083679
The present invention relates to a method and a device for processing a hard-coated, in particular planar workpiece surface of a rotationally symmetrical, in particular disk-shaped workpiece with at least one grinding wheel. The invention relates in particular to the processing of a hard-coated brake disk.
Known for processing conventional brake disks are methods and devices, in which the brake disk is driven into a rotational motion around a workpiece axis of rotation, and the grinding wheel is driven into a rotational motion around the grinding wheel axis of rotation, wherein the workpiece axis of rotation and the grinding wheel axis of rotation are aligned parallel to each other, so that the workpiece surface of the brake disk to be processed and the processing surface of the grinding wheel are also aligned parallel to each other. During the processing operation, the grinding wheel and brake disk thus abut against each other over a large area.
In the brake disks commonly in use today, during braking the ablation of the brake disk and of the brake pad generates fine dust, which contaminates the outside air, but can also become deposited on rims as dirt. In addition, oxidation of the brake disk can negatively influence the first braking operation after a prolonged period of nonuse. Therefore, it has already been proposed that the surfaces of brake disks be provided with hard particles, so that the brake disks become more corrosion-resistant. For example, tungsten carbide particles are applied to the brake disks by laser sintering. However, the surfaces of the hard-coated brake disks must still be processed to achieve the required surface properties (for example, dimensional and shape accuracy and roughness). However, as the result of the hard coating advantageous for reducing the fine dust load, the hard-coated brake disks cannot be adequately processed with conventional methods and machines, since large forces are required to process the surfaces of the hard-coated brake disks.
Therefore, the object of the present invention is to indicate a method and a device with which a hard-coated brake disk can be efficiently processed.
The object is achieved by a method and a device with the features of the respective independent claim. Advantageous further developments of the method and the device are indicated in the dependent claims, wherein individual features of the advantageous further developments can be combined with each other in a technically reasonable manner. In particular, the features and advantages disclosed with reference to the method can be applied to the device and vice versa.
In particular, the object is achieved by a method for processing a hard-coated and in particular planar workpiece surface of a rotationally symmetrical workpiece with at least one grinding wheel, comprising at least the following steps:
The object is also achieved by a device for processing a hard-coated and in particular planar workpiece surface of a rotationally symmetrical surface, comprising:
In other words: The basic idea of the invention provides that the grinding wheel be angulated to the workpiece during the processing operation (i.e., while the grinding wheel is in contact with the workpiece and both are rotationally driven). Accordingly, the grinding wheel axis of rotation and workpiece axis of rotation are not parallel during this processing operation. In the case of a planar workpiece surface, the workpiece surface is thus also not parallel to the planar processing surface of the grinding wheel. As a result of such an angulation, the grinding wheel is in contact with the workpiece surface during the processing operation with a smaller surface (preferably in a quasi-linear or even just quasi-punctiform manner). As a consequence, given an identical application of force, the pressure between the workpiece surface and the grinding wheel can be increased, thereby resulting in an improved ablation of the hard-coated workpiece surface. For example, the angulated grinding wheel can thus be in contact with the workpiece surface to be processed only at one punctiform or linear location during its initial use, while the shape of the contact location can vary as processing continues due to the wearing of the grinding wheel.
In principle, it would be sufficient to provide exactly one grinding wheel driving device for each workpiece driving device, so that exactly one side of the workpiece can be processed with the one grinding wheel. The other side of the workpiece could then potentially be processed in a later processing step with the same grinding wheel. However, it is preferred that the device for the one (or each) workpiece driving device have a second grinding wheel driving device for generating a rotational motion around a second grinding wheel axis of rotation, which is arranged in particular in such a way that a second, in particular planar workpiece surface of the rotationally symmetrical workpiece lying opposite the first workpiece surface can be processed with a second grinding wheel that rotates around the second grinding wheel axis of rotation. The two grinding wheels preferably have opposite rotational directions. In particular a second angulating device for angulating the second grinding wheel axis of rotation to the workpiece axis of rotation is provided for the second grinding wheel driving device, so that the second grinding wheel axis of rotation and the workpiece axis of rotation are not parallel while processing the second workpiece surface. The second workpiece surface can be processed simultaneously with the first workpiece surface with a second grinding wheel driving device and a second angulating device, wherein the angulation of the second grinding wheel to the workpiece axis of rotation also enables a higher ablation on the second workpiece surface.
In this conjunction, it is provided in particular that the second grinding wheel driving device be operated synchronously (inversely) to the first grinding wheel driving device. Therefore, the amount of the (first) angle of incidence between the (first) grinding wheel axis of rotation and the workpiece axis of rotation is equal to the amount of the (second) angle of incidence between the second grinding wheel axis of rotation and the workpiece axis of rotation during the processing operation. As a consequence, for example, both sides of a brake disk can be processed simultaneously and identically. The device is preferably set up in such a way that the two grinding wheel driving devices can be swiveled independently of each other but in opposite directions relative to a machine frame during the processing operation.
In particular during the implementation of only exactly one grinding wheel driving device, it may be enough for angulating the grinding wheel axis of rotation and the workpiece axis of rotation relative to each other to have exactly one angulating device, with which either the grinding wheel driving device is angulated to the workpiece driving device, or with which the workpiece driving device is angulated to the grinding wheel driving device. In the advantageous configuration of two grinding wheel driving devices, it is preferred that each grinding wheel driving device have allocated to it an angulating device, so that the two grinding wheel driving devices can be angulated relative to the workpiece driving device.
In particular, a grinding wheel can be angulated to the workpiece by means of a swiveling motion by exactly one rotational degree of freedom. In this case, then, the corresponding angulating device has exactly one rotational degree of freedom. However, it can also be provided that the angulation allow a swiveling motion around two or more rotational degrees of freedom. Accordingly, the or each angulating device has two rotational degrees of freedom, or the workpiece axis/axes of rotation or the grinding wheel axis of rotation can be swiveled around two rotational degrees of freedom.
For example, the at least one angulating device can have one or several (swiveling) axis/axes, spherical surface(s), calotte surface(s) or solid state joints for realizing the one degree of freedom or several degrees of freedom.
The angulating device preferably comprises a sleeve-shaped outer body, in which the workpiece driving device is mounted so that it can swivel around one or several rotational degrees of freedom. The sleeve-shaped outer contour can preferably be linearly fed in exactly one direction or in all three spatial directions. If the angulating device can only be linearly fed in one spatial direction, the workpiece driving device can preferably be linearly fed in one or several (two or three) spatial direction(s). In an embodiment, an angulating drive can be secured to the sleeve-shaped outer body for each rotational degree of freedom.
In order to bring the at least one grinding wheel into contact with the workpiece surface, at least one infeed device must be provided, with which the workpiece (or its workpiece driving device) and the grinding wheel (or its grinding wheel driving device) can be fed in relative to each other. In principle, it would be sufficient to provide only one infeed device (for the workpiece driving device or the grinding wheel driving device), with which a relative motion can be performed parallel and/or orthogonally to the workpiece axis of rotation. However, it is preferred that at least one infeed device be provided, with which the workpiece (or the workpiece driving device) can be moved in a plane orthogonal to the workpiece axis of rotation (in particular radially to the workpiece axis of rotation) to the grinding wheel driving devices that are preferably allocated in particular to a respective angulating device. However, it can also be provided that each grinding wheel driving device have allocated to it an infeed device, with which the grinding wheel driving device can be moved in a plane orthogonally to the workpiece axis of rotation and/or axially.
An especially preferred embodiment provides that the grinding wheel and the workpiece be moved relative to each other in a plane perpendicular to the workpiece axis of rotation during the processing operation. Accordingly, at least one infeed device is set up in such a way that the grinding wheel(s) and the workpiece can be moved relative to each other during the processing operation in a plane perpendicular to the workpiece axis of rotation. Accordingly, then, the rotating grinding wheel (or the rotating grinding wheels) are moved on a path arranged in the plane perpendicular to the workpiece axis of rotation relative to the rotating workpiece (in particular in a radial direction linearly toward the workpiece axis of rotation or away from the latter). In this way, the entire workpiece surface of a side of the workpiece to be processed can be processed by means of the grinding wheel, and a desired crosscut can possibly be generated.
In this conjunction, it is provided in particular that the grinding wheel(s) be angulated to the workpiece preferably designed as a brake disk, while the grinding wheels are not (yet) in contact with the workpiece surface. For processing purposes, this is followed by a relative motion in a plane orthogonal to the workpiece axis of rotation, so that the grinding wheels process the workpiece surfaces of the brake disk from radially outside to radially inside (and thereafter possibly in the opposite direction). A high ablation can be achieved in this way.
It can also be provided that the (first) angle of incidence between the (first) grinding wheel axis of rotation and the workpiece axis of rotation and possibly also the (second) angle of incidence between the second grinding wheel axis of rotation and the workpiece axis of rotation be changed during the processing operation. Therefore, the angle of incidence is changed while the workpiece surface is in contact with the grinding wheel. As wear on the grinding wheel increases, the effective processing surface between the grinding wheel and workpiece surface increases with the grinding wheel angulated, so that changing the angle of incidence makes it possible to reduce the effective processing surface, as a result of which the pressure between the grinding wheel and workpiece surface is in turn increased. As a consequence, the ablation rate can be changed, adjusted, or corrected during the processing operation.
In another advantageous embodiment of the invention, which can also be regarded as an independent invention and thus be claimed without the angulation described above between the grinding wheel and workpiece, it is provided that the at least one grinding wheel be conditioned while being processed, i.e., dressed and/or sharpened, for example. Accordingly, the device comprises at least one conditioning device, which can be brought from an initial position into a conditioning position, so that the grinding wheel can be conditioned during the processing operation. The grinding wheel is thus conditioned while the grinding wheel itself is in contact with the workpiece. For example, the conditioning device can be brought into contact with the rotating grinding wheel during the processing operation at a location lying opposite the processing location of the grinding wheel with the workpiece. To this end, for example, the conditioning device being mounted so that it can swivel, and preferably move in an axial direction of the workpiece axis of rotation, can be brought by means of a suitable drive from the initial position into the position referred to as the conditioning position, in which the grinding wheel happens to also be in contact with the conditioning device.
It is additionally proposed that the workpiece surface be processed with the angulated grinding wheel(s) in a first processing step, while the workpiece axis of rotation and grinding wheel axis of rotation are aligned parallel to each other in a subsequent processing step, so that the grinding wheel(s) abut(s) against the (respective) workpiece surface with a relatively large surface area. A relatively high ablation of material from the hard-coated workpiece surface thus takes place in the first processing step with the angulated grinding wheel, while a higher surface quality (for example dimensional accuracy and/or required roughness) can be achieved in the subsequent processing step.
In particular, it is proposed that the following steps be performed in the specified sequence, which results in an especially short overall processing time:
In order to correct an ablation of the workpiece surface (and/or the grinding wheel) that took place during the processing operation, the at least one grinding wheel and the workpiece can be fed to each other in particular parallel to the workpiece axis of rotation.
In particular, the device comprises a controller, which is set up to implement the described method.
The invention along with the technical environment will be exemplarily explained below based on the figures, wherein the figures only show a preferred embodiment. Shown schematically on:
The device shown on
The device additionally comprises a first grinding wheel driving device 4a, which is mounted in a first angulating device 6a, and can be used to drive a first grinding wheel 2a into a rotational motion around a grinding wheel axis of rotation 2a.1. The device additionally has a second grinding wheel driving device 4b, which is mounted in a second angulating device 6b, and can be used to drive a second grinding wheel 2b into a rotational motion around a second grinding wheel axis of rotation 2b.1. The angulating devices 6a, 6b will still be explained in detail with reference to
The device additionally comprises a first conditioning device 7a, which can be brought into a conditioning position from an initial position, and used to dressed the grinding wheels 2a, 2b. The device additionally comprises a second conditioning device 7b, which likewise can be brought into a conditioning position from an initial position, and used to sharpen the grinding wheels 2a, 2b.
The first angulating device 6a and a first grinding wheel driving device 4a mounted therein will now be explained in more detail with reference to
The first angulating device 6a and the second angulating device 6b can be fed in by undepicted drives in at least the horizontal direction.
In order to process the brake disk 1, both the brake disk 1 and the grinding wheels 2a, 2b are rotationally driven, wherein the grinding wheels 2a, 2b are each brought into contact with a side of the brake disk 1. It is now proposed that, while processing the brake disk 1, the grinding wheels 2a, 2b be angulated in opposite directions in such a way that the first grinding wheel axis of rotation 2a.1 and the second grinding wheel axis of rotation 2b.1 not be aligned parallel to the workpiece axis of rotation 1.1. Such a nonparallel angulation of the grinding wheels 2a, 2b can take place by means of the angulating devices 6a, 6b.
In the following (see upper and middle image on
At the end of the peeling motion 8a, a piercing motion can take place along the arrows 8b, during which the grinding wheels 2a, 2b are moved toward the brake disk 1 parallel to the workpiece axis of rotation 1.1. In order to further improve the surface quality (dimensional accuracy, roughness) of the brake disk 1, the grinding wheel axes of rotation 2a.1, 2b.1 are initially aligned parallel to the workpiece axis 1.1 by a swiveling motion (denoted by arrows 8c) (see middle image on
As may also be discerned from
1 Workpiece
1.1 Workpiece axis of rotation
2
a First grinding wheel
2
a.1 First grinding wheel axis of rotation
2
b Second grinding wheel
2
b.1 Second grinding wheel axis of rotation
3 Workpiece driving device
4
a First grinding wheel driving device
4
b Second grinding wheel driving device
5 Infeed device
6
a First angulating device
6
a.1 First swivel axis
6
a.2 Second swivel axis
6
a.1i First angulating drive
6
a.2i First angulating drive
6
a.3 Inner bearing sleeve
6
a.4 Second bearing sleeve
6
a.5 Outer sleeve
6
b Second angulating device
7
a First conditioning device
7
b Second conditioning device
8
a Peeling motion
8
b Piercing motion
8
c Aligning motion
8
d Corrective motion
| Number | Date | Country | Kind |
|---|---|---|---|
| 21196493.7 | Sep 2021 | EP | regional |
