Apparatus for machining borders of flat workpieces

Abstract

The invention relates to an apparatus (1) for machining edges on borders (10) of flat workpieces (8), for example glass panes, the apparatus comprising two tools in the form of grinding rings (6). The tools each have a first effective surface, for example a grinding surface (7), and, in addition to the first grinding surface (7), a second effective surface, for example a grinding surface (9). The tools, for example the grinding rings (6), can be used for abrasive machining or polishing. When the first grinding surface (7) is worn out, the second grinding surface (9) can be used for machining after the grinding rings (6) have been reversed or exchanged in order to position the second grinding surfaces (9) of the grinding rings (6) so that they face each other.

Description

[0001] DEVICE FOR MACHINING THE EDGES OF FLAT WORKPIECES

[0002] The invention relates to a device for machining the edges of flat workpieces, such as glass panes, having the features of the introductory part of claim 1.

[0003] Devices for machining the edges of flat workpieces, especially glass panes, are known in various designs. For example, there are devices with grooved grinding wheels. Reference is made to WO 2015 / 055671 A1, EP 1 607 177 B1, and EP 1 488 886 B1.

[0004] Belt grinders are known from EP 1 344 604 B1 or DE 44 19 963 G1 for the removal of material from flat workpieces, in particular glass panes, in order to trim their edges.

[0005] In US 9,555,516 B2 it has been proposed to have cup-shaped grinding wheels act on the edges of the edges of glass panes, with one grinding wheel acting on one edge and another grinding wheel acting on the other edge.

[0006] Edge trimming devices with sanding belts (so-called "belt sanders"), particularly with sanding belts arranged in a cross shape, have the advantage that the sanding belts can be flexibly applied to the edges of the workpiece. Therefore, the accuracy of the positioning of the workpiece (e.g. the glass pane) to the pane belts is not critical. Overlaps and breaks resulting from edge surfaces that are not at right angles to the plane of the glass pane but are inclined, or even workpiece shapes that deviate slightly from the desired shape due to cutting tolerances, as well as rejected (non-flat) workpieces, can be edged without any problem. Deviations of the flat workpiece, such as a glass pane, from the specified shape and size are compensated for by the flexibility of the sanding belts.

[0007] Trimming devices that use grinding wheels, which generally have a V-profile and are suitable for different glass thicknesses, are generally rigidly mounted, so that inaccuracies in the shape and size of the flat workpiece to be machined (glass sheet), as well as deformations of the workpiece (the workpiece is warped, i.e., not flat), must be compensated for by the machine. It is therefore necessary to take measures to track the edges to be machined, as is known, for example, from EP 2 512 732 B1. The known trimming wheels (grinding wheels with a V-profile) often cause the problem that edges are not machined evenly as desired at overcuts and undercuts.

[0008] US 2,733,553 A shows and describes a tool for grinding knives or the like. The tool has two grinding wheels secured to two sleeves by means of nuts. The sleeves are mounted on a shaft rotated by a motor and are held in a central position by springs, where they rest against each other.

[0009] During grinding, the grinding wheels of the device known from US 2,733,553 A can be moved against the force of the springs so that the edges on both sides of a knife or the like can be machined.

[0010] The tool known from US 2,733,553 A is used for sharpening knives and similar cutting tools. Sharpening cutting tools, on the one hand, and machining edges on flat workpieces, such as glass panes, on the other, have different underlying tasks.

[0011] When cutting flat workpieces, especially glass panes, deviations from the desired size and shape, diagonal breaks such as overcuts and undercuts, and a deviating geometry can occur (e.g., when cutting glass panes, a cut in the shape of a rhombus or parallelogram is created instead of a rectangle or square). Trimming such edges that deviate from the specified position and size presents a problem because a satisfactory hem cannot be achieved without additional, rather complex, mechanical engineering measures on the workpiece (glass pane).

[0012] From WO 2021 / 013779 A1, it is known to use slip rings rotated about an axis in a device for trimming plate-shaped workpieces, such as glass panes. The slip rings, which engage the edges of the workpiece in a removing manner, are axially movable, allowing them to follow the edges of the workpiece during trimming. The slip rings automatically engage the edges of the workpiece to be trimmed, even if the edges are not in the specified desired position. The slip rings are mounted in a floating manner on their carrier via hydrostatic bearings or gas bearings. In the known device, the slip rings have only one active surface (grinding surface) that is inclined to their axis. This means that worn (worn) slip rings must be replaced with new ones.

[0013] Wheels for engraving glass are well known. These wheels have V-shaped, profiled peripheral edges coated with abrasive material, with a sharp edge that creates the engraving. For example, reference is made to "Grooving wheels - shape V" from Tyrolit (www.tyrolit.com). These known wheels are intended solely for engraving glass, whereby a glass surface is machined with the free edge of the V-shaped peripheral edge to create engravings, i.e., grooves, in the glass surface. DE 78 05 264 U1 discloses a device for chamfering the outer and / or inner edge of a hollow glass, whereby the front edge of the glass must be ground perpendicular to its axis.

[0014] The bending device known from DE 78 05 264 U1 has a working tool that acts against the edge of a hollow glass with predetermined, elastic, and adjustable pressure. During the bending process, the working tool is moved against the edge of the hollow glass, with the hollow glass itself rotating about a vertically aligned axis. The bending tool comprises two separately arranged grinding wheels, each having two truncated cone-shaped grinding surfaces covered with a diamond concretion.

[0015] The invention is based on the object of providing a device in which complex conversion work is not required when grinding rings are worn out.

[0016] This object is achieved according to the invention with a device having the features of claim 1.

[0017] Advantageous and preferred embodiments of the device according to the invention are the subject of the dependent claims.

[0018] The device according to the invention comprises at least one grinding ring with two active surfaces, such as grinding surfaces, which act on the edges of the flat workpiece in an abrasive or polishing manner for the removal or polishing of edges on the edges of flat workpieces, such as glass panes.

[0019] The device according to the invention can be designed and configured for both grinding (trimming) and polishing the edges of workpieces. Since in the device according to the invention the at least one slip ring has two active surfaces for machining the workpiece, for example, grinding surfaces, it is sufficient, after one of the active surfaces has been worn, to align the slip ring, for example, by turning it, so that the other—not yet worn—active surface can be used for machining the workpiece.

[0020] For example, the at least one slip ring of the device according to the invention has two active surfaces facing away from each other, both of which are at an acute angle to the axis of rotation of the slip ring.

[0021] The angles enclosed by the effective surfaces of the slip rings with the rotational axis of the slip rings can be the same or different.

[0022] If the angles of the active surfaces (grinding surfaces) of the grinding rings are equal - as is preferred - this has the advantageous effect that active surfaces that are not yet worn (e.g. unused) can be used to machine flat workpieces by turning the grinding wheel or both grinding wheels over.

[0023] If one of the active surfaces of the slip ring is worn, it is sufficient to turn the slip ring over (invert it). If two slip rings are provided, the slip rings can be swapped. After swapping the slip rings, unused active surfaces face each other and the device according to the invention can be used with "fresh", i.e., unused active surfaces (grinding surfaces) for machining workpieces, for example for grinding (trimming) or polishing the edges of glass panes. If the active surfaces of a slip ring enclose different angles with the rotational axis of the grinding wheel, it is possible to achieve different machining results on the flat workpiece with one slip ring.For example, with one effective surface a chamfer can be produced which is at an angle of 45 ° to the plane of the flat workpiece and after turning the grinding ring with the other effective surface a chamfer can be produced which is at a different angle to the plane of the workpiece, for example 60 °.

[0024] Advantageously, the at least one slip ring can be mounted in a floating manner on its carrier (the inner diameter of the slip ring is larger than the outer diameter of the carrier), so that the slip ring can move freely on its carrier in the direction of the (rotational) axis.

[0025] The floating bearing of the slip ring on the carrier can be designed as a hydrostatic bearing or as a gas (air) bearing.

[0026] The exemplary design of the device with a hydrostatic bearing or gas bearing has the advantage that the coupling of the slip ring with its carrier, with which coupling the torque is transmitted from the carrier to the slip ring, can be designed in such a way that the floating bearing of the slip ring is not adversely affected.

[0027] Within the scope of the invention, it can be provided that the at least one grinding ring is elastically spring loaded so that when the device is used, it rests against the edge of the edges of the workpiece with elastic prestress.

[0028] If springs are provided, in a possible embodiment of the invention with two slip rings, these cause the slip rings with their slip surfaces to be moved back into the initial position of the slip surfaces after use of the device.

[0029] A spring-loaded slip ring, as well as two independent spring-loaded slip rings, provide the ability to follow the edges of the workpiece when the distance between the edge of the workpiece and the axis around which the device is rotated changes (becomes larger or smaller), i.e. does not remain in the desired position.

[0030] The device according to the invention combines, in an exemplary embodiment with at least one spring-loaded grinding ring, preferably two spring-loaded grinding rings, the advantages of belt grinders with those of grinding wheels, since the active surface of the grinding ring or the active surfaces of the grinding rings in this embodiment are designed to be elastically flexible, i.e. they rest against the edges of the workpiece under elastic (spring) prestress.

[0031] The coupling of the at least one slip ring of the device according to the invention with its carrier can be achieved in different ways within the scope of the invention.

[0032] In one embodiment of the invention, it is provided that a pin with a sliding guide is received in a bore or recess in the slip ring.

[0033] The design of the coupling between the at least one slip ring and its carrier in the form of a pin which is fastened to the carrier and engages in a bore or recess in the slip ring, provided in one embodiment of the invention, allows the floating bearing of the slip ring in the form of a hydrostatic bearing or a gas bearing to be designed without influence from the coupling between the slip ring and its carrier in such a way that a good bearing of the slip ring is ensured.

[0034] The coupling of at least one slip ring with its carrier in order to transmit torque from the carrier to the slip ring can also be effected by a tongue and groove arrangement.

[0035] In a preferred embodiment of the invention, the active surfaces, such as grinding surfaces, are provided on two slip rings which are arranged on the carrier so as to be movable relative to one another in the direction of the (rotational) axis and are resiliently loaded towards one another.

[0036] As a rule, two slip rings are provided on the carrier of the device according to the invention.

[0037] However, within the scope of the invention, embodiments are also considered in which more than one pair of slip rings is provided on the carrier.

[0038] If two or more than two slip rings and / or pairs of slip rings are provided on the carrier, slip rings with differently shaped grinding surfaces can be arranged on the carrier.

[0039] The at least one grinding ring provided within the scope of the invention can be designed for abrasive processing (e.g. grinding and trimming) and also for polishing the edges of workpieces.

[0040] If two or more than two slip rings are provided in the device according to the invention, a

[0041] Slip rings are designed with raised portions (protrusions) on their sides. Such raised portions have the beneficial effect of preventing the slip rings from sticking together.

[0042] In a possible embodiment of the device according to the invention, it can be provided that the first active surface, such as a grinding surface, and the second active surface, such as a grinding surface, enclose an acute angle, in particular 45°, with the axis of the carrier.

[0043] In a possible embodiment of the device according to the invention, it can be provided that the active surfaces, like the grinding surfaces, point in opposite directions and are preferably symmetrical to the center plane of the grinding ring.

[0044] In a possible embodiment of the device according to the invention, it can be provided that a carrier for the slip ring is provided which is driven in rotation about an axis, and that the slip ring is coupled to the carrier for rotation.

[0045] In a possible embodiment of the device according to the invention, it can be provided that the slip ring is arranged on the carrier so as to be movable in the direction of the axis.

[0046] In a possible embodiment of the device according to the invention, it can be provided that two slip rings or more than two slip rings are arranged next to one another on the carrier.

[0047] In a possible embodiment of the device according to the invention, it can be provided that the slip ring is arranged so that it can be removed from the carrier.

[0048] In one possible embodiment of the device according to the invention, it can be provided that the slip ring is mounted floatingly on the carrier, in particular via a hydrostatic bearing or gas bearing. In one possible embodiment of the device according to the invention, it can be provided that at least one pin is provided as a driver and / or guide for coupling the slip ring to the carrier, that the pin is fastened to the carrier, and that the pin engages in a bore or recess in the slip ring.

[0049] In a possible embodiment of the device according to the invention, it can be provided that the pin is received in the bore or recess of the slip ring with sliding guide.

[0050] In a possible embodiment of the device according to the invention, a tongue and groove arrangement can be provided for coupling the slip ring to the carrier.

[0051] In a possible embodiment of the device according to the invention, it can be provided that the slip ring is elastically spring loaded.

[0052] In a possible embodiment of the device according to the invention, it can be provided that the first and second active surfaces, such as grinding surfaces, are conical or concave.

[0053] In a possible embodiment of the device according to the invention, it can be provided that the slip rings are arranged on the carrier so as to be displaceable in the direction of the axis.

[0054] In one possible embodiment of the device according to the invention, it can be provided that the slip rings are biased toward one another by springs. In one possible embodiment of the device according to the invention, it can be provided that the slip rings are biased toward one another by pneumatic or hydraulic springs.

[0055] In a possible embodiment of the device according to the invention, it can be provided that at least one line for the supply of liquid or gaseous medium, such as water or air, is provided in the carrier, and that line branches branch off from the line and open between the inner surface of the slip ring and the outer surface of the carrier.

[0056] In a possible embodiment of the device according to the invention, it can be provided that at least one annular space is provided which is partially delimited by the slip ring, and that the line for supplying the liquid or gaseous medium opens into the annular space.

[0057] The term "spring" used herein includes any type of elastic means acting on a slip ring or on the slip rings. Examples are: metallic springs (coil springs), gas springs (pneumatic springs) and fluid springs.

[0058] Further details, features, and advantages of the invention will become apparent from the following description of the exemplary embodiments illustrated, partly schematically, in the drawings. It shows:

[0059] Fig. 1 in axial section two grinding rings during the hemming of a glass pane,

[0060] Fig. 2 shows an embodiment with two grinding rings on a carrier,

[0061] Fig. 3 shows a section through another embodiment of the device, Fig. 4 shows a section through a slip ring,

[0062] Fig. 5 shows the slip ring from Fig. 4,

[0063] Fig. 6 in oblique view the slip ring from Fig. 4 and 5,

[0064] Fig. 7 in oblique view a further embodiment of the

[0065] Device and

[0066] Fig. 8 shows a section of the device from Fig. 7.

[0067] The embodiment of a device 1 shown in Fig. 2 comprises a carrier 12 serving as a (drive) shaft and two slip rings 6. The slip rings 6 are arranged on the carrier 12 so as to be displaceable in the direction of the axis 2 of the carrier 12, as indicated in Fig. 2 by the arrows 13.

[0068] A line 14 for fluid supply (water supply) is provided in the carrier 12, so that the slip rings 6 are mounted on the carrier 12 via hydrostatic bearings (floating). Instead of hydrostatic bearings for the slip rings 6, gas (air) bearings can also be provided. In the case of gas bearings, gas (e.g., air) is supplied via line 14.

[0069] Supplied liquid (water) can escape through the gap 15 between the slip rings 6 in the direction of the workpiece 8 (the glass pane to be machined), so that the workpiece 8, e.g. the glass pane, is cooled at its edge 10 by the liquid during machining in addition to the cooling by water sprayed onto the workpiece from nozzles.

[0070] The grinding rings 6 have as active surfaces first grinding surfaces 7, which are conically or concavely curved and, when the device 1 is used to machine the edges of an edge 10 of the workpiece 8 to be machined (glass pane), for example to form bevels, act in a removing or polishing manner.

[0071] The slip rings 6 of the embodiment shown in Fig. 2 are loaded by springs 16, in the example helical springs, which are arranged between the slip rings 6 and shoulders 17 of the carrier 12, in the sense of a movement towards each other.

[0072] Since the slip rings 6 on the carrier 12 are loaded by the springs 16, the slip rings 6 can follow the contour of the edge 10 of the workpiece 8 to be machined (glass pane) without the need for special guidance measures. The reason for this is that the grinding surfaces 7 of the slip rings 6 are elastically resilient and, under spring preload, adhere to the edges of the workpiece 8 to be machined, such as a glass pane, even if the edge 10 of the workpiece 8 deviates from the desired position.

[0073] In order to couple the slip rings 6 to the carrier 12 for rotation, pins 18 are provided on one of the flanges 17 for torque transmission, which engage with sliding guides through bores 20 provided in the slip rings 6.

[0074] The slip rings 6 provided in the device 1 according to the invention have, in addition to the first grinding surfaces 7 (active surfaces), second grinding surfaces 9 (active surfaces). This is shown in the schematic diagram in Fig. 1. The grinding surfaces 7 and 9 carry, for example, a diamond coating 21 as an abrasive agent (see Fig. 1).

[0075] The second grinding surfaces 9 of the slip rings 6 point away from the first grinding surfaces 7 of the slip rings 6.

[0076] Both the first grinding surfaces 7 and the second grinding surfaces 9 of the slip rings 6 form an acute angle with the axis 2, in particular an angle of 45°.

[0077] The angles formed by the first grinding surfaces 7 and the second grinding surfaces 9 with the axis 2 in the embodiments of the device 1 according to the invention shown in the drawings are preferably equal. However, embodiments in which the grinding surfaces 7 and 9 form different (acute) angles with the axis 2 are also contemplated within the scope of the invention.

[0078] It can be seen that the grinding rings 6 with grinding surfaces 7 and 9, which enclose equal angles with the axis 2, can be turned in order to align the second grinding surfaces 9 instead of the first grinding surfaces 7 in such a way that the second grinding surfaces 9 point towards one another and can be used for machining a workpiece 8.

[0079] The turning of the slip rings 6 is carried out as soon as the first grinding surfaces 7 are worn (worn out).

[0080] The step of arranging the second grinding surfaces 9 of slip rings 6 with grinding surfaces 7 and 9, which enclose equal angles with the axis 2, so that they point towards one another and can be used to machine the edges on an edge 10 of the workpiece 8, can also be carried out by exchanging the two slip rings 6. Thus, the slip ring 6 initially on the left in Fig. 2 takes the place of the slip ring 6 initially on the right in Fig. 2, and the slip ring 6 initially on the right in Fig. 2 takes the place of the slip ring 6 initially on the left in Fig. 2.

[0081] In order to be able to turn or swap the slip rings 6, the carrier 12 is divided, as indicated in Fig. 2, so that the part 22 arranged on the right in the example in Fig. 2 can be removed from the other part of the carrier 12 after loosening connecting means (screws or threads) not shown. After removing the part 22, the slip rings 6 can be pulled off the carrier 12 and pushed back onto the carrier 12 after being turned or swapped places. In the embodiment of the device 1 according to the invention shown in Fig. 3, a plurality of pins 18, which are arranged at different distances from the axis 2, are provided to transmit the torque from the carrier 12 to the slip rings 6. The pins 18 engage slidingly in bores 20 in rings 25 and 26.

[0082] The slip ring 6 arranged on the left in Fig. 3 is connected to the radially outer ring 25 by screws 27, wherein a disk 28 is provided between a flange 29 of the outer ring 25 and the grinding disk 6.

[0083] The slip ring 6 arranged on the right in Fig. 3 is connected via screws 32 to a pot 30 which is fastened to the radially inner ring 26 by screws 31.

[0084] The assembly, comprising the left-hand grinding ring 6 in Fig. 3, the disk 28, and the outer ring 25, is displaceable on the carrier 12 relative to the right-hand grinding disk 6 in Fig. 3 in the direction of the axis 2. Thus, the distance between the grinding disks 6 can be adjusted to the thickness of the flat workpiece 8 (glass disk).

[0085] In addition, the assembly, comprising both slip ring 6, the radially inner ring 26 and the radially outer ring 25, is mounted on the carrier 12 so as to be movable in the direction of the axis 2 because it is floating.

[0086] In the embodiment of the device 1 according to the invention shown in Fig. 3, the carrier 12 is composed of several parts. These parts are a hollow core 33, a sleeve 34 receiving the core 33, two end disks 35 and a cap screw 36 which closes the hollow space in the core 33 at one end. In the embodiment of the device 1 shown in Fig. 3, due to regions 40, 41 of the rings 25 and 26 having different sliding diameters, a hydraulic or pneumatic spring force results which loads the slip rings 6 towards one another. Fig. 3 shows that the sliding diameter between the right-hand end of the outer ring 25 in Fig. 3 and the adjacent right-hand end of the inner ring 26 (region 40) is smaller than the sliding diameter at the end shown in Fig. 3 left ends of rings 25 and 26 (area 41).Under the effect of the fluid (air or water) flowing through the line branches 24, the spring force which presses adjacent slip rings 6 against one another is generated by the areas 40 and 41 with different sliding diameters. In order for the spring force which presses adjacent slip rings 6 against one another to occur, a throttleable relief bore 51 which leads through the flange 29 to the outside is provided in the radially outer ring 25. Fluid such as water which is supplied centrally through the line 14 can flow out through the relief bore 51 in addition to flowing out through the bearing gap. At the outer end of the relief bore 51 there is a throttle point which can be adjusted by means of a throttle screw 52.The magnitude of the spring force pressing the slip rings 6 together can be determined by selecting the quantity of supplied fluid, such as water, on the one hand, and by adjusting the throttle cross-section of the throttle point, on the other. In Fig. 3, the relief bore 51 is shown symbolically as a dashed line for the sake of clarity, and the throttle screw 52 as a rectangle. A relief bore corresponding to the relief bore 51 and having a throttle point can also be provided in the embodiment of the device 1 shown in Fig. 8 and, for example, lead to the outside through the sleeve 48.

[0087] The embodiment of a slip ring 6 shown in Figs. 4 to 6 has six elevations 43 (protrusions) on each side surface 42 of the slip ring 6, which prevent the side surfaces 42 of adjacent slip rings from lying flat against one another. This prevents slip rings 6 from sticking to one another. The elevations 43 have a small height, on the order of tenths of a millimeter, for example, 0.1 mm.

[0088] The embodiment of the device 1 according to the invention shown in Figs. 7 and 8 comprises an arrangement with springs 45 engaging in grooves 44 for transmitting the rotation of the carrier 12 to the slip rings 6. In the example shown in Figs. 7 and 8, grooves 44 are provided in a flange 46 projecting radially from the carrier 12. The springs 45, which engage in the grooves 44, are strips screwed to a flange 47 projecting radially outward from a sleeve 48.

[0089] The sleeve 48, on which the slip rings 6 sit and are held by a nut 49, is movable on the carrier 12 in the direction of arrow 13 via a fluid bearing, e.g., a hydrostatic bearing or a pneumatic bearing. The fluid (air or water) flows through the line 14 and the line branches 24 into the annular space 37 between the core 33 of the carrier 12 and the sleeve 48, forming hydrostatic or pneumatic bearings 50 next to the space 37. The fluid exits again between the core 33 and the sleeve 48.

[0090] In summary, an embodiment of the invention can be described as follows:

[0091] A device 1 for machining edges 10 of flat workpieces 8, for example glass panes, has two tools in the form of grinding rings 6. The tools each have a first effective surface, for example a grinding surface 7, and in addition to the first grinding surface 7, a second effective surface, for example a grinding surface 9. The tools, for example the grinding rings 6, can be used for removing or polishing. When the first grinding surface 7 is worn, the second grinding surface 9 can be used for machining after the grinding rings 6 have been turned or exchanged in order to arrange the second grinding surfaces 9 of the grinding rings 6 so that they face one another.

Claims

Claims:

1. Device (1) for machining edges on edges (10) of flat workpieces (8), for example glass panes, with at least one slip ring (6) which has a first active surface, in particular a grinding surface (7), characterized in that the at least one slip ring (6) has, in addition to the first active surface, such as a grinding surface (7), a second active surface, such as a grinding surface (9).

2. Device according to claim 1, characterized in that the first active surface, such as a grinding surface (7), and the second active surface, such as a grinding surface (9), enclose an acute angle, in particular 45°, with the axis (2) of the carrier (12).

3. Device according to one of claims 1 or 2, characterized in that the active surfaces, such as the Grinding surfaces (7 and 9) point in opposite directions and are preferably symmetrical to the center plane of the slip ring (6).

4. Device according to one of claims 1 to 3, characterized in that a carrier (12) driven in rotation about an axis (2) is provided for the slip ring (6), and that the slip ring (6) is coupled to the carrier (12) for rotation.

5. Device according to one of claims 1 to 4, characterized in that the slip ring (6) is arranged on the carrier (12) so as to be movable in the direction of the axis (2).

6. Device according to claims 1 to 5, characterized in that on the carrier (12) next to each other two slip rings (6) or more than two slip rings (6) are arranged.

7. Device according to one of claims 1 to 6, characterized in that the slip ring (6) is arranged to be removable from the carrier (12).

8. Device according to one of claims 1 to 7, characterized in that the slip ring (6) is mounted on the carrier (12) in a floating manner, in particular via a hydrostatic bearing or gas bearing.

9. Device according to one of claims 1 to 8, characterized in that for coupling the slip ring (6) to the carrier (12) at least one pin (18) is provided as a driver and / or guide, that the pin (18) is fastened to the carrier (12) and that the pin (18) engages in a bore (20) or recess in the slip ring (6).

10. Device according to claim 9, characterized in that the pin (18) is received in the bore (20) or recess of the slip ring (6) with a sliding guide.

11. Device according to one of claims 1 to 8, characterized in that a tongue and groove arrangement (44, 45) is provided for coupling the slip ring (6) to the carrier (12).

12. Device according to one of claims 1 to 11, characterized in that the slip ring (6) is elastically spring loaded.

13. Device according to one of claims 1 to 12, characterized in that the first and the second Effective surfaces, such as grinding surfaces (7 and 9), conical or are concave.

14. Device according to one of claims 6 to 13, characterized in that the slip rings (6) are arranged on the carrier (12) so as to be displaceable in the direction of the axis (2).

15. Device according to claim 14, characterized in that the slip rings (6) are biased towards each other by springs (11).

16. Device according to claim 15, characterized in that the slip rings (6) are loaded by pneumatic or hydraulic springs.

17. Device according to one of claims 1 to 16, characterized in that at least one line (14) for the supply of liquid or gaseous medium, such as water or air, is provided in the carrier (12), and that line branches (24) branch off from the line (14) and open between the inner surface of the slip ring (6) and the outer surface of the carrier (12).

18. Device according to claim 17, characterized in that at least one annular space is provided which is partially delimited by the slip ring (6), and that the line (14) for supplying the liquid or gaseous medium opens into the annular space.

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