EP1616664B1 - Polishing process for polishing of rotationally symmetric workpieces - Google Patents

Abstract

The workpiece (F) is dipped into a container (12) filled with abrasive and moved relative to the abrasive container. The workpiece is then moved up and down vertically, turned on its central axis (B) and moved inside the container on its central axis.

Description

The present invention relates to a method for machine polishing of rotationally symmetrical workpieces, in particular vehicle rims, in which the workpiece is immersed in a container filled with polishing agent and moved relative to the polishing agent container (see. DE-A-26 20 477 ).

Such surface treatment methods are basically known. In this case, the polishing agent container is filled with polishing bodies and detergent compositions in order to achieve an effective surface treatment.

Although previous polishing methods allow a polishing of a workpiece or a vehicle rim to a certain extent. Nevertheless, it is not possible with the known polishing method to achieve such a surface treatment or refinement that the rim has the appearance of a chromed rim. In addition, no effective processing in deeper pockets or recesses can be done.

It is the object of the invention to provide a method for machine polishing of workpieces, with the the appearance of a chrome-plated workpiece can be created without requiring chrome plating.

The solution of this object is achieved by the features of claim 1.

Advantageous embodiments of the invention are described in the description, the drawings and the subclaims.

According to a first advantageous embodiment, the central axis of the workpiece can be moved along an orbital path, for example a circular path, which has a diameter of about 10 to 35% of the diameter of the workpiece. It has been found that an orbital path with a relatively small diameter surprisingly leads to exceptionally good results, although the path of movement of the workpiece through the container filled with polishing agent is only comparatively short. An advantageous diameter of an orbital path can be about 100 to 300 mm.

At least one stirring element can be provided in the container and rotated. By such a stirring element, the polishing effect can be additionally increased by the relative movement between the workpiece and polishing bodies is increased. It is particularly advantageous here if the stirring element is rotated in the interior of the workpiece and / or below the workpiece. This makes it possible, on the one hand, to satisfactorily polish even partial areas of the workpiece. On the other hand, can be created by such a method, a workpiece polished on both sides, for example, a rim that can be used for motorcycles.

A particularly good polishing effect results when the stirring element is rotated counter to the direction of rotation of the workpiece.

According to a further advantageous embodiment, a wobbling motion can additionally be imposed on the workpiece in order to further increase the relative movement between the polishing agent and the workpiece.

According to a particularly advantageous embodiment, the rim can not be oscillated only during the process step C), that is, during the rough polishing and the fine polishing, but not during the high-gloss polishing, the rim in the container in the vertical direction is moved up and down.

According to a further embodiment of the method according to the invention, it is advantageous during the method steps A), B) and C) to change the oscillation frequency of the vertical movement at least once, in particular to reduce it to at least 50%. It may also be advantageous during the process steps A), B) or C) the minimum or maximum immersion depth of the rim in the container at least once to change.

Also by the use of selected polishing agents, the polishing process according to the invention can be optimized. After numerous experiments, the inventors have found that it can be particularly advantageous if the specific weight of the polishing agent used in process step A) is greater than in process step B), but less than in process step C).

Good results have also been achieved by choosing the maximum rotational speed and orbital motion speed to be less than about 150 rpm.

According to an advantageous embodiment, the chuck is attached to a vertical shaft, that is, the rim is rotated in the polishing agent container about a vertically extending axis of rotation. hereby can be avoided in the polishing agent container unwanted wave formation, which adversely affects the polishing process.

A structurally particularly advantageous embodiment results when the orbital drive has a gear that is coupled to the rotation device. In this way, both the rotational movement as well as the orbital motion can be done with the help of a single drive. For example, a planetary gear can be provided, wherein the planetary gear transmits the rotational movement and a sun gear orbital motion.

According to a further embodiment of the invention, at least one. Be provided stirring element which is rotatably driven about a vertical axis. As a result, on the one hand causes an increased relative movement between the polishing agent and the workpiece. On the other hand, the vertically arranged rotation axis prevents unwanted wave formation within the polishing agent. Here, the stirring element can be arranged either in the region of the chuck in order to achieve an upwardly facing inner region of the workpiece. Alternatively or additionally, the stirring element may be arranged in the region of the polishing agent container, for example above the container bottom.

A particularly simple construction is given in an embodiment in which the stirring element is fixed to a vertical shaft which extends coaxially and preferably within a shaft to which the chuck is attached.

In individual process steps, it may be advantageous to oscillate the workpiece and to rotate, but not suspend any orbital motion. For such a method step, according to another aspect of the invention, there is provided an apparatus for machine polishing workpieces having a polishing agent container, a chuck attached to a shaft for fixing at least one workpiece, and an oscillating means oscillating the polishing agent container or chuck in the vertical direction , Furthermore, a rotation device is provided, which sets the chuck about a central axis in rotation. A stirring element is attached to a vertical shaft which is coaxial with the shaft to which the chuck is attached. With such a device, the stirring element below or even within the workpiece, such as a vehicle rim, be rotated to achieve the desired polishing effects.

Although the movement of the workpiece is preferably described above relative to the polishing agent container, it is always assumed that it is fundamentally irrelevant to the invention whether the movements described are achieved by movement of the workpiece or alternatively by movement of the container. In the described embodiment, however, not the container but only the rim is moved, since this requires a lower equipment and design effort.

In addition, it should be noted that the inventive method is basically suitable for all rotationally symmetrical workpieces, although the application is preferred in rims. Possible here All types of rims or wheels, ie rims for cars, trucks or motorcycles in all sizes and variations.

Hereinafter, the present invention will be described purely by way of example with reference to an advantageous embodiment and with reference to the accompanying drawings.

Fig. 1

eine Seitenansicht einer ersten Ausführungsform einer Poliervorrichtung; und

Fig. 2

einen Teil einer Poliervorrichtung gemäß einer weiteren Ausführungsform.

Show it:

Fig. 1

a side view of a first embodiment of a polishing apparatus; and

Fig. 2

a part of a polishing apparatus according to another embodiment.

The polishing apparatus shown in Fig. 1 comprises a base frame 10, on which a polishing agent container 12 is arranged. The polishing agent container 12 is formed in the illustrated embodiment, round and open at the top, but may also be trough-shaped or trough-shaped. The polishing agent container 12 is not in any fixed connection with the base frame 10 and can thus be easily replaced by industrial trucks. To increase the polishing agent movement, a vibration drive may additionally be provided. Furthermore, various inflow and outflow options are provided on the polish container 12 in order to continuously add or remove water and / or treatment agents (compounds). In operation, the container 12 is filled to about the level of level N with polishing agent.

At the bottom of the container 12, a stirring element 14 is provided, which has a plurality of parallel to the bottom extending paddle, which is driven by a drive 16, which is located below the container bottom, about a vertical axis of rotation D rotating.

Further, a machine stand 18 is arranged on the base frame 10, on which a cross-beam 20 in the vertical direction, that is along the double arrow X, slidably mounted. The vertical movement is effected via a drive 22, not shown, which causes a raising and lowering of the cross-beam 20 in conjunction with a lifting cylinder 24. Here, the cross-beam along the axis A in the direction of the double arrow X is raised or lowered. In the position shown in Fig. 1, the cross-beam 20 is in an upper position corresponding to the loading and unloading position, that is, from the position shown, the cross-beam 20 can be moved down.

At the outer end of the cross-beam 20, a vertical hollow shaft 26 is provided, at the outer end of a chuck 28 is mounted, which serves for fastening a rim F. The hollow shaft 26 is in this case attached to a planetary gear 30, which is driven by a drive 32 and via (not shown) toothed belt. In this way, the hollow shaft 26 and thus the chuck 28 and thus also the rim F via the drive 32 on the one hand rotated about its own central axis B. On the other hand, the rim F with its central axis B along a closed, circular in the illustrated embodiment, orbit around the central axis C of the planetary gear 30 in led an orbital motion. Thus, the drive 22 causes the oscillating movement of the rim F along the axis A in the direction of the double arrow X and the drive 32, both the rotational movement of the rim F about its central axis B as well as the orbital movement about the axis C.

Inside the hollow shaft 26, a further shaft 34 is provided, at the lower end of a stirring device 38 is attached, which dips into the interior of the rim F. For rotating the stirring device 38 about the axis B, another drive 40 is used.

As shown in FIG. 1, the axis of rotation D, which is arranged approximately in the middle of the container 12, approximately coaxial with the axis of rotation C of the planetary gear 30 runs.

By appropriately blocking the planetary gear 30, an operating mode can also be achieved in which the rim F indeed rotates about the axis B, but does not perform any orbital movement about the axis C. Such an operation may prove advantageous in individual process steps.

All drives 16, 22, 32 and 40 are speed-controlled and reversible in their direction of rotation. All drives are connected to a (not shown) machine control in which the desired workflows can be programmed arbitrarily.

In the apparatus described above, the hollow shaft 26 has an offset of about 100 mm to the rotation axis C.

FIG. 2 shows a further embodiment of a polishing apparatus, wherein like reference numerals are used for parts which are the same as in FIG. 1.

In Fig. 2, the cross-beam 20 is shown a further embodiment of the polishing apparatus, which differs from the embodiment shown in Fig. 1 in that not only one chuck but a plurality of chucks 28 ', 28 "respectively to hollow shafts 26', 26" attached are. The hollow shafts 26 'and 26 "are in turn attached to a planetary gear 30, which is driven by the drive 32. The chucks 28' and 28" thus rotate about the central axis C of the planetary gear 30 and additionally about the central axes B and B 'of the hollow shafts 26 'and 26 ".

It is understood that the number of chucks that are moved by the planetary gear along an orbital path is basically not limited.

The polishing method according to the invention is described below with reference to the polishing apparatus of FIG. 1, which basically has the method steps A) rough polishing, B) fine polishing and C) high-gloss polishing.

In this case, all information with regard to the polishing body and the compound means to the product names of the company Rösler Oberflächentechnik GmbH, Staffelstein, Germany.

A) rough polishing

In this first process step polishing bodies of the type TP / S are used with a specific gravity of about 1.82 g / cm ³ . The bulk density of the polishing agent is about 1.0 to 1.31, in particular 1.25 kg / l. Preference is given to polishing bodies having a pyramidal shape. However, cone, paraboloid, triangular and double wedge shapes may also be used singly or in admixture. The polishing body may be made of plastic or ceramic. The compound used is FCAL232 and water.

For rough polishing, the container 12 is filled with TP / S polishing bodies. The polishing body filling height should preferably reach the upper edge of the rim to be immersed. During processing, 100 l water / h and 1.2 l FCAL232 are added.

The polishing time can vary between about 10 and 60 minutes.

The rough polishing preferably proceeds in the following two steps:

Step 1:

The rim F is clamped with its visible side down in the chuck 28 and is moved at a speed of 100 rev / min about the axes B and C. Subsequently, the rim F is retracted into the container 12 and moved up and down by approximately 24 strokes / min within the polishing body. Here, the immersion depth changes between about 70 mm and 170 mm. The processing time is depending on the casting quality the aluminum rim F between 16 and 34 min, with preferably 50% counterclockwise and 50% clockwise.

2nd step:

In this second process step of the rough polishing, the process parameters described above are varied as follows: The immersion depth is 90 to 190 mm and the speed of the rim is 25 rpm. 3 to 4 strokes / min are carried out, wherein the processing time is preferably about 6 minutes with about 3 minutes clockwise rotation and 3 minutes counterclockwise rotation.

B) Fine polishing

In this second process step, a mixture TP / FS with the shapes and sizes between 0 and 25 mm described above is used as the polishing body. The specific gravity of the polishing bodies is about 1.6 g / cm ³ . The bulk density of the polishing agent is about 0.85 to 1.22, in particular 1.03 kg / l. The compound used is again FCAL232 (2.5 l / h) and water 150 l / h). The processing time is about 12 to 25 minutes.

Also, the process step of the fine polishing is divided into the following two process steps:

Step 1:

The editing process here is basically similar to the The rough polishing described above, that is, the speed of the rim F is about 100 U / min at 20 strokes / min. The immersion depth of the rim within the polishing body is about 70 to 170 mm. The processing time is about 10 minutes with 4 minutes clockwise rotation and 4 minutes counterclockwise rotation.

2nd step:

In this second process step, the speed of the rim is about 25 to 34 rpm at 20 strokes / min. The immersion depth varies between 90 and 190 mm. The processing time is 6 minutes with 3 minutes clockwise rotation and 3 minutes counterclockwise rotation.

C) mirror polishing

In this last process step are used as a polishing body TP / PL 5.6 GK with a specific gravity of about 2.4 g / cm ³ . The bulk density of the polishing agent is about 0.65 to 4.91, in particular 1.51 kg / l. The compound used is FCAL232 together with water. The filling height of the polishing body corresponds to the water level in the container. Appropriately, an increased liquid level is set here, whereby a good rinsing of the workpieces is achieved with the polishing bodies. At the same time an optimal lightening and polishing is achieved. During processing, water is metered in at 20 to 30 l / h and compound at approx. 1.5 l / h. Again, there is a two-step processing:

Step 1:

In this method step, the planetary gear 30 is blocked so that only one rotation of the rim F about the axis B but no orbital motion takes place about the axis C. The speed here is about 60 to 80 rev / min at 10 to 15 strokes / min. The immersion depth is between about 95 and 155 mm. The processing time is about 14 minutes with 3 minutes clockwise and 3 minutes counterclockwise.

2nd step:

Here, the speed is chosen to be about 25 to about 35 rpm at 10 to 15 strokes / min. The immersion depth is about 55 to 155 mm. The processing time is about 8 minutes with 2 minutes clockwise and 2 minutes counterclockwise.

Subsequent to the process step C) of high-gloss polishing, the application of a corrosion protection and / or a lacquer can be followed, which does not change the optical properties of the rim.

By a stepless change in the process water levels, a different aggressiveness of the polishing agent can be effected.

LIST OF REFERENCE NUMBERS

10

base frame

12

container

14

stirrer

16

drive

18

machine stand

20

crossbeam

22

drive

24

lifting cylinder

26, 26 ', 26 "

hollow shaft

28, 28 ', 28 "

chuck

30

planetary gear

32

drive

34

wave

38

stirrer

40

drive

A

axis

B, B ', C, D

axis of rotation

F

rim

N

Polishing body level

X

stroke direction

Claims (8)

1. A method for the machine polishing of a rotationally symmetrical workpiece, for example of a vehicle rim, in which the workpiece is immersed into a container filled with a polishing medium and is moved relative to the polishing medium container, wherein the polishing comprises the following process steps:

   A) rough polishing;

   B) fine polishing;

   C) high gloss polishing,

   characterized in that
   the bulk weight of the polishing medium used lies in the range from 1.0 to 1.3 kg/l in process step A); in the range from 0.8 to 1.3 kg/l in process step B); and in the range from 0.5 to 5 kg/l in process step C)
2. A method in accordance with claim 1, characterized in that the workpiece is simultaneously:

   a) moved up and down in the vertical direction in the container (oscillation);

   b) rotated about its own central axis (rotation); and

   c) moved with its central axis along a closed orbital track in the container (orbital movement).
3. A method in accordance with claim 2, characterized in that the workpiece is not oscillated only during one process step, in particular during process step C).
4. A method in accordance with one of the preceding claims 2 or 3, characterized in that the oscillation frequency and/or the rotational speed is changed at least once, is in particular reduced to at least approximately 50%, during the process steps A), B) and C).
5. A method in accordance with any one of the preceding claims 1 to 4, characterized in that the minimum or the maximum immersion depth of the workpiece in the container is changed at least once during the process steps A), B) or C).
6. A method in accordance with any one of the preceding claims 1 to 5, characterized in that the specific weight of the polishing medium used in process step A) is selected to be larger than in process step B), but smaller than in process step C).
7. A method in accordance with claim 2, characterized in that the maximum speed of the rotational movement and of the orbital movement is selected to be lower than approximately 150 rpm.
8. A method in accordance with any one of the preceding claims, characterized in that the polishing medium includes liquid; and in that the liquid level is changed continuously.

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