EP3157708B1 - Method and device for finish machining of peripheral surfaces of rotationally symmetrical workpiece sections - Google Patents

Description

AREA OF APPLICATION AND PRIOR ART

The invention relates to a method for finish machining peripheral surfaces of rotationally symmetrical workpiece sections and to a device suitable for carrying out the method.

Finishing, which is also referred to as superfinishing, is a machining process with indefinite cutting edges. By finishing work surfaces of rotationally symmetric or non-rotationally symmetrical workpiece sections on workpieces such as crankshafts, camshafts, transmission shafts or other components for power and working machines can be edited to produce a desired surface fine structure. When finishing in the piercing process, a finishing tool with granular cutting agent is pressed against the peripheral surface to be machined. To produce the cutting speed required for the material removal, the workpiece is rotated about its workpiece axis. At the same time, a relative movement that oscillates parallel to the workpiece surface is produced between the workpiece and the finish tool resting against the peripheral surface. Through the combination of the rotational movement of the workpiece and the superimposed oscillatory motion, a so-called cross-cut pattern can be created, whereby the machined workpiece surfaces e.g. As running surfaces for plain bearings or bearings or the like are particularly suitable. The workpiece section to be machined may be, for example, a main bearing or a crank bearing of a crankshaft or a camshaft bearing.

In contrast to grinding, finishing is a thermally neutral processing method in which no soft skin interspersed with microcracks or surface tensions arises. Finishing is often used after a grinding process as the last machining process of a process chain to remove the soft skin, re-exposing the original microstructure, increasing the support of the roughened surface structure, and improving the component geometry in terms of roundness and shortwave errors in the axial and circumferential directions.

Grinding is the last shaping machining operation. When grinding, the geometry of the grinding tool of the machine control is known, so that the workpiece can be contoured by grinding according to the guided by the machine control tool guide. A prerequisite for this shaping is the regular dressing or calibration of the grinding tools. However, the grinding process is usually unable to achieve the achievable by the finish machining surface properties.

In the finishing machining of rotationally symmetrical bearing points, the preservation of the axial contour is usually in the foreground. An improvement in the form values on cylindrical bearings takes place mainly in the radial direction and is highly dependent on the pre-processing. For example, short-wave error components, e.g. with more than 15 waves on the circumference, are relatively reliably improved, while long-wave components, such as e.g. Ovals, triangles or quadrilaterals can not be positively influenced by finishing. The cutting volume through the finishing process is usually less than 10 μm. In order to obtain the best possible geometry, the material removal of the finishing process is normally adjusted to the pre-processing.

Grinding is usually the last shaping machining operation. This means that the contouring of a rotationally symmetrical bearing point essentially takes place through the grinding process preceding the finishing process. A continuous dressing of the grinding wheel is imperative for the shaping and design of the bearing. Depending on the requirement and the drawing tolerance of the bearing, the dressing cycle is reduced or extended. However, the grinding process is usually unable to achieve the achievable by the finish machining surface properties.

When machining bearing sections on shafts, the geometry requirements are often such that individual or all bearing sections should have a slightly spherical shape. A crowned (barrel-shaped, convex) shape of rotationally symmetric bearing sections can help to reduce bearing damage due to flight and form errors of the components interacting in the bearing. Corresponding, specified by the customer final generatrix requirements regarding crowning are usually expressed in diameter differences of a few micrometers between different axial positions of the bearing section.

When grinding crankshaft bearing sections, a crowned macro-shape can be achieved by appropriate dressing of the circumferential surfaces of the grinding wheels used during grinding (cf. EP 1 181 132 B1 . Fig. 5 ).

The EP 1 514 642 A2 describes a device for finish machining of shafts, in particular crankshafts and camshafts, with a tool carrier and an endless abrasive belt, which has a flexible carrier and an abrasive layer with hard material. The device is used for processing a rotating about its axis of rotation workpiece. A sanding belt drive continuously drives the sanding belt during workpiece machining. There is provided a clamping device for the grinding belt. The tool carrier has a machining head with two mutually spaced band deflections, which limit a working range of the machining head, wherein the grinding belt is guided over the tape deflections and passes in the work area on the peripheral surface of the workpiece to be machined. The circulating abrasive belt outside of the work area is associated with a device for dressing the abrasive layer, which has a deliverable during the workpiece processing against the abrasive layer of the belt at a speed adjusted to the workpiece processing belt speed adjustable dressing tool. In one embodiment, the dressing tool has a convex contour transverse to the direction of tape travel, which is transferred to the abrasive layer during dressing. As a result, a slightly convex contour can be generated on the machined workpiece section.

The DE 10 2011 087 252 B3 , which forms the basis for the preamble of claim 3, describes an apparatus for finishing machining a particular annular workpiece, comprising a carrier for connection to a finishing tool holder for holding a finishing tool and drive means for generating a linear oscillating movement of the carrier , An oscillation unit is provided which has a finish tool holder for receiving a finish tool and an auxiliary drive means for generating a linear oscillation movement of the finish tool holder. Furthermore, a connection device for connecting the oscillation unit with the carrier is provided.

TASK AND SOLUTION

It is an object of the invention to provide a method and apparatus for a finishing process which allow not only to obtain and, if necessary, to slightly improve the resulting shape values of machined workpiece sections with the aid of the finish machining from a rough machining, but if necessary also be able to influence and create or change it. In particular, the possibility should be created to produce non-cylindrical workpiece sections with predefinable spherical shape by means of finishing.

To achieve this object, the invention provides a method having the features of claim 1. Furthermore, a device suitable for carrying out the method is provided with the features of claim 3. Advantageous developments are specified in the dependent claims. The content of all claims is incorporated herein by reference.

In the claimed invention, the finish tool or the relevant for the material removal, provided with cutting means part of the finishing tool during a rectilinear Linear motion parallel to the axis of rotation of the workpiece imposed on a linear motion of this pivotal movement, so that the abrasive part of the finish tool is guided along an at least partially curved tool path.

As a result, different, axially juxtaposed axial sections on the machined workpiece section can be finishen specifically with different degrees of material removal, whereby a desired, in the axial direction not rectilinear generating line form can be selectively generated. The generatrix shape can thus be changed by means of a special machine configuration with respect to the generatrix line resulting from the preprocessing. Thus, a shaping processing by Finishen is possible.

In some processing variants, the control of the machine is carried out so that in an end phase of a linear stroke of the linear machine axis leading in the direction of movement of the linear motion leading end portion of the finish tool closer to the workpiece axis and / or is pressed with higher local contact force to the peripheral surface than a trailing rear end section. As a result, generally convex or spherical shapes can be achieved. The forms include, in particular, a full-crowned generatrix line shape, a cylindrical-crowned generatrix line shape or a cylindrical-logarithmic generatrix line shape.

In terms of design, this can be realized in a device in that compared to conventional machine concepts, an additional or more specifically controllable machine axis, namely a rotary machine axis, is provided to a two-dimensional, almost arbitrary by a superposition of two linear axes of motion and a rotation axis Trajectory for the finish tool to realize.

A robust and reliably working variant of a device is characterized in that the translatory machine axis has a horizontal slide comprising a rotary machine axis with a rotary table which relative to the carriage by means of a numerically controlled rotary drive, for example a servo motor, corresponding to one of the pivot axis horizontal axis of rotation is rotatable. The rotary table may carry a stone guide having a translatory machine axis to move the tool holder along a feed direction which is perpendicular to the pivot axis and corresponds to the pressing direction.

It would also be possible to combine the machine axes in other ways, for example by providing a rotary machine axis with a rotary table carrying a linear guide for a translatory machine axis.

It is also possible that the rotary axis is realized as an integrated into the finish tool axis, that is located on the tool side of the tool holder. This also makes it possible to achieve that the abrasive cutting means along the desired arcuate Runway is constrained, for example, to generate a spherical shape on the workpiece section.

BRIEF DESCRIPTION OF THE DRAWINGS

• Fig. 1 eine Seitenansicht einer Bearbeitungssituation bei einem Ausführungsbeispiel eines Verfahrens zur Finish-Bearbeitung einer Umfangsfläche eines Werkstücks;
• Fig. 2 eine axiale Ansicht der Bearbeitungssituation aus Fig. 1;
• Fig. 3 Details zur Kinematik der Werkzeugbewegung;
• Fig. 4 ein Ausführungsbeispiel einer Vorrichtung zur Durchführung des Verfahrens in Seitenansicht (Fig. 4A) und Vorderansicht (Fig. 4B); und
• Fig. 5 ein Ausführungsbeispiel eines Finish-Werkzeugs mit integrierter Schwenkachse.

Further advantages and aspects of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are explained below with reference to the figures. Showing:

• Fig. 1 a side view of a processing situation in an embodiment of a method for finish machining a peripheral surface of a workpiece;
• Fig. 2 an axial view of the machining situation Fig. 1 ;
• Fig. 3 Details on the kinematics of the tool movement;
• Fig. 4 An embodiment of an apparatus for performing the method in side view ( Fig. 4A ) and front view ( Fig. 4B ); and
• Fig. 5 an embodiment of a finishing tool with integrated pivot axis.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Based on Fig. 1 and 2 some interrelations and terms helpful in understanding embodiments of the invention will be explained. It shows Fig. 1 a side view of a typical machining situation in an embodiment of a method for finish machining a peripheral surface 195 of a rotationally symmetrical workpiece section on a workpiece 190. The workpiece is rotated by means of a rotating device for generating a rotational movement of the workpiece about a workpiece rotation axis or workpiece axis 192 at a constant rotational speed. The workpiece section to be machined may, for example, be a main bearing of a crankshaft or a bearing surface of another shaft, for example a camshaft or a balancing shaft.

In order to effect a material removal on the workpiece section by means of finishing, a finishing tool 100 with a pressing force F acting in a pressing direction AR is pressed against the circumferential surface to be machined or onto the workpiece section to be machined. For this purpose, the finishing machine has a corresponding pressing device.

The removal of material is supported by the fact that an oscillating relative movement between the workpiece and the finishing tool aligned parallel to the workpiece surface is produced by means of an oscillation device (see double arrow OSZ). In the example case, the oscillation device is mounted on the side of the finish tool, so that the finish tool is oscillated in an oscillation direction OR perpendicular to the pressing direction AR, while the workpiece rotates only about the workpiece axis 192. The oscillation device here comprises a pneumatic oscillator, which can move the finish tool relative to the tool holder 180.

Furthermore, a translatory machine axis (numerically controlled linear axis) is provided which can effect a linear movement of the finishing tool superimposed on the oscillatory movement in a linear lifting direction LR which runs parallel to the workpiece axis 192. If required, this linear movement (double arrow LIN) can take place over a linear stroke length which is greater than the oscillation stroke.

Furthermore, a rotary axis (numerically controlled axis of rotation) for generating a linear movement of the superimposed pivotal movement of the finishing tool is provided. The pivoting movement (curved double arrow SW) takes place about a pivot axis SA, which is perpendicular to the workpiece axis and perpendicular to the pressing direction AR.

The control of the finishing machine is configured in the example so that a pivotal position of the finishing tool, i. the current rotational position about the pivot axis SA, in response to an axial position of the linear movement LIN is controllable. Thus, the orientation of the oscillation direction OSZ with respect to the machine coordinate system in the example, a function of the axial position of the linear movement and the pivot position and is phased not parallel, but at varying acute angle to the workpiece axis.

The finish tool 100 mounted on the free end of a tool holder 180 has a cutting means carrier 110 which is typically made of tool steel or other metallic material and includes means for mounting the finish tool to the tool holder 180 at its rear. On the front of the cutting medium carrier, a cutting pad 120 is attached, for example, by means of an adhesive or by means of screws. The cutting coating formed by a sintered material contains a plurality of cutting agent grains, which are distributed in the example homogeneously within a matrix of a binder. Cutting agent grains may be, for example, diamond grains or cubic boron nitride (CBN) grains. As a binder, for example, a ceramic or a metallic material into consideration.

The cutting coating normally has a rectangular cross section on its base side facing the cutting medium carrier. By definition, the longitudinal direction L of the cutting pad is that direction which, in the finish machining, is substantially parallel to the workpiece rotational axis. Perpendicular to the longitudinal direction L, the transverse direction Q extends in such a way that the longitudinal direction and transverse direction lie in a plane perpendicular to the pressing direction.

On the side facing away from the cutting medium carrier, the cutting coating forms an abrasive, concave-cylindrical cutting surface 125 with which the cutting coating bears more or less extensively on the peripheral surface to be processed during the finish machining. As in Fig. 2 is clearly visible, the cutting surface in the transverse direction Q has a concave shape whose radius of curvature substantially corresponds to the desired radius of curvature of the machined workpiece portion at the end of the finish machining.

Based on the schematic Fig. 3 For example, details of the kinematics of tool motion in creating a full crowned axial geometry of a workpiece portion 194 of the workpiece 190 will be discussed. The conditions are not drawn to scale. The workpiece 190 rotates about its workpiece axis 192. The finish tool 100 is pressed by means of the pressing device in the pressing direction AR to the rotationally symmetrical workpiece outer surface. The finishing tool oscillates relative to the tool carrier in the oscillation direction OSZ perpendicular to the pressing direction. The oscillation movement is superimposed on a linear movement LIN running parallel to the workpiece rotation axis 192, for which a numerically controlled linear axis of the finishing machine is provided.

The linear stroke, ie the stroke length of the linear movement, is in Fig. 3 exaggerated. Typically, the oscillation stroke is in the range of a few millimeters, for example in the range of ± 0.5 mm to ± 3 mm. The additionally achievable by the linear movement stroke can be in the same order of magnitude, that is, for example, between 1 mm and 3 mm. Other stroke lengths and stroke length ratios are possible.

The axis-parallel linear movement is superimposed on a pivoting movement of the finishing tool about a perpendicular to the linear direction and perpendicular to the pressing direction pivot axis. In order to achieve the illustrated convex, ie barrel-shaped shape of the peripheral portion, the pivoting movement is controlled so that in an end phase of a Linearhubs, ie in the second half of a Linearhubs after exceeding a central position, according to a control program in the direction of movement of the linear motion vorseilender front end portion of the finish tool is closer to the workpiece axis 192 and is pressed against the peripheral surface with a higher local pressure force than one in the direction of movement trailing rear end section. For example, if the finish tool moves in the first direction R1 in FIG Fig. 3 to the left, the front end portion E1 is pressed with stronger local pressing force to the workpiece surface than the trailing second end portion E2. In the middle phases of the linear lifting movement, the pressing direction is oriented perpendicular to the workpiece rotation axis and both end sections of the finishing tool are pressed against the peripheral surface with approximately the same local contact pressure When approaching the turning point on the other side (in the second direction R2), the second end portion E2 now leads the first end portion E1 and is pressed against the peripheral surface with a stronger local pressing force than the first end portion E1.

The maximum swing angle of the pivotal movement, i. the maximum angle between the instantaneous orientation of the pressing direction and the zero point position (pressing direction perpendicular to the workpiece rotation axis 192) is normally very small and is generally below 1 °, possibly also below 0.1 °. The swivel angle may be e.g. in the range 0.01 ° to 0.1 °.

The oscillation direction OR always runs with this kinematics parallel to the workpiece surface in an axial plane containing the workpiece axis 192. The pressing force acts in this kinematics, regardless of the axial position of the finishing tool always substantially in the normal direction to the currently machined part of the workpiece section, ie perpendicular to the workpiece surface. With a uniform rotational speed of the workpiece and a uniform oscillation frequency, the local removal of material is essentially determined by the locally prevailing pressing force, so that the convex surface line can be produced with the aid of the finish machining.

In order to achieve that the desired pressing force is determined independently of the local diameter of the currently machined part of the workpiece section solely by the actuation of the pressing device, the linear movement and the pivoting movement is superimposed on a linear compensating movement extending in the pressing direction.

It can be seen that other axial geometries can be produced according to the same principle. If, for example, the pivoting movement is designed in such a way that the pressing direction AR remains aligned in a wider area about the axial center of the peripheral section perpendicular to the workpiece rotation axis 192 and the finishing tool is pivoted only in the final phases near the turning points, then a cylindrical-crowned axial direction can be achieved Geometry are generated, in which in the central region, a cylindrical part of the workpiece section which is rounded to the axial edges to reduce the diameter. Also, a cylindrical-logarithmic or a concave generatrix line shape can be produced in this way.

The degree of crowning given, for example, by the difference in radius ΔR between the region of greatest radius or diameter and the region of smallest radius or diameter is normally of the order of a few micrometers, for example between 1 and 5 μm.

Based on Fig. 4 an embodiment of a device 400 for finishing peripheral surfaces is explained, with which the special tool kinematics can be realized. Fig. 4A shows a side view parallel to the direction of movement of a horizontal, linear machine axis, which executes the linear stroke. Fig. 4B shows a front view of the device in a direction perpendicular to this linear direction horizontal direction, which corresponds to the axial direction of a rotary machine axis.

On a vertical support 410 of the device, a linear machine axis LA is provided with a horizontal axis direction. Through this, the described linear motion is generated. The linear machine axis includes a horizontal slide 420, which is guided along horizontal guide rails 425 and is moved by means of a servo motor (not shown) via a ball screw. The carriage 420 carries a rotary machine axis, which comprises a rotary table 430 which can be rotated relative to the carriage 420 by means of a numerically controlled rotary drive about a horizontal axis of rotation corresponding to the pivot axis SA. The rotatable about the pivot axis rotary table 430 carries on its front side a so-called stone guide 440 which includes a translational machine axis to move the tool holder 180 along a direction perpendicular to the pivot axis SA extending feed direction, which corresponds to the pressing AR. At the front end of the tool holder, the finish mold 100 is mounted, which cuts the workpiece 190 which is driven for processing using a rotation device so that it around its workpiece axis of rotation 192 (at a predetermined speed, for example between 50 min ^-1 and 300 min ^-1 turns.

The device can work as follows. While the workpiece 190 is rotated about the workpiece axis 192, the finish tool 100 performs a rapid oscillation in the oscillation direction OR along the movement axis of the oscillator. In addition, an interpolating movement is superimposed by the stone guide to the finishing tool to produce an axial geometry of the machined workpiece section. The stone guide For this purpose, it executes a relatively slow and large stroke along the horizontal direction of movement of the linear axis LA. At the same time, the rotary table 430 pivots the stone guide 440 about the pivot axis SA, while the linear axis, which can move the tool holder 180 linear, causes a corresponding length compensation. In this way, an arcuate tool path is imposed on the finish tool. This can be produced by finishing a round or any other axial tool path on the machined workpiece section, whereby a corresponding generatrix line shape can be generated on the workpiece.

By changing the pivot angle in conjunction with the movement of the linear machine axis LA all conceivable contours in the axial direction of the machined peripheral portion are to be designed and influenced. Convex as well as concave line shapes of the generatrix can be achieved.

As a result of the possibility thus created of being able to influence the generatrix shape of bearing points in the axial direction in a targeted manner by means of finishing, it may be possible in future production processes to dispense with the finish grinding which precedes conventional processes. Due to the fact that the finish machining can now be designed as a shaping treatment, the finishing process no longer depends on the pre-processing or is less dependent on the pre-processing. If necessary, the finishing process can also be designed more efficiently with a larger cutting volume. The previously customary dressing cycles for grinding tools after a certain number of processed bearings may possibly be dispensed with using this novel finish technology. A high oscillation frequency of the oscillation movement (typically at least 10 Hz) parallel to the axial contour ensures a self-sharpening effect of the finish tool, so that a dressing of a finishing tool unlike grinding tools is not required. Thus, the process chain can be significantly reduced and investments can be saved.

In the example shown so far, the rotary pivot axis is a machine axis, while the finish tool is a conventional passive finish tool. In other embodiments, can be dispensed with a rotary pivot axis in the finishing device. Instead, the pivoting movement or a corresponding pivot axis can be integrated into an actively activatable finish tool. Fig. 5 shows an example of a finishing tool 500 with integrated pivot axis. The cutting medium carrier 510 of the finishing tool 500 is constructed in several parts. A machine-side fixed part 512 is firmly fastened to the tool carrier 110 with suitable fastening means. The fixed part carries a relative to the fixed part of the movable part 514, which is opposite to the fixed part by a Swivel axis SA is limited pivot. The cutting pad 520 is attached to the front of the movable part 514. The pivotal movement of the movable part with cutting surface with respect to the fixed part is accomplished by means of actuators ACT, which may be constructed using piezo elements, for example. The actuators are controlled via the control unit of the finishing device and cause a pivoting of the movable part relative to the fixed part in dependence on the linear movement of the translational axis parallel to the workpiece rotation axis.

In this variant, the movable part 514 with the cutting pad 520 may be considered a finishing tool, while the fixed part 512 may be considered part of the tool holder 180. The variant of FIGS. 1, 2 and 4 then differs from the variant Fig. 5 in that in the first case, the pivot axis is arranged on the machine side of the tool holder and in the latter case on the tool side of the tool holder.

Claims (7)

1. Method for the finish-machining of circumferential surfaces of rotationally symmetrical workpiece portions on workpieces, in the case of which, during the machining of a circumferential surface, a finishing tool (100, 500) is pressed by way of a pressure-exerting force, in a pressure-exerting direction (AR), onto the circumferential surface which is to be machined and, for material-removal purposes, the workpiece is rotated about a workpiece axis (192) and an oscillating relative movement is generated between the finishing tool and the workpiece, wherein,
   in order to generate the oscillating relative movement, the finishing tool is moved back and forth along an oscillation direction (OR) running perpendicularly to the pressure-exerting direction (AR) with a predeterminable oscillation-stroke length and oscillation frequency;
   the oscillation movement is accompanied by a linear movement of the finishing tool over a linear-stroke length, said linear movement running parallel to the workpiece axis, and
   the linear movement and the oscillation movement are accompanied by a pivoting movement of the finishing tool about a pivot axis (SA) running perpendicularly to the workpiece axis and to the pressure-exerting direction,
   wherein a pivoting position of the finishing tool is controlled in dependence on an axial position of the linear movement such that
   in an end phase of a linear stroke, a leading, front end portion of the finishing tool, as seen in the movement direction of the linear movement, is located closer to the workpiece axis, and/or is pressed onto the circumferential surface by way of a higher local pressure-exerting force, than a trailing, rear end portion,
   wherein the finish-machining generates, by varying a surface-line shape which results from prior machining, a circumferential portion which has a fully crowned, a cylindrical crowned or a cylindrical logarithmic axial geometry.
2. Method according to claim 1, characterized in that the pivoting movement is accompanied by a linear compensating movement of the finishing tool in the pressure-exerting direction (AR).
3. Device for the finish-machining of circumferential surfaces of rotationally symmetrical workpiece portions on workpieces, comprising:

   a rotating device for generating a rotary movement of the workpiece (190) about a workpiece axis (192);

   a pressure-exerting device for pressing a finishing tool (100) onto a circumferential surface (195) which is to be machined such that the finishing tool is pressed onto the circumferential surface by way of a pressure-exerting force, in a pressure-exerting direction (AR); and

   an oscillation device for generating an oscillating movement of the finishing tool in relation to the workpiece along an oscillation direction (OR) running perpendicularly to the pressure-exerting direction (AR) with a predeterminable oscillation-stroke length and oscillation frequency;

   characterized by
   a translatory machine axis (LA) for generating a linear movement of the finishing tool, said linear movement accompanying the oscillation movement and running parallel to the workpiece axis; and
   a rotary axis for generating a pivoting movement of the finishing tool, said pivoting movement accompanying the linear movement, about a pivot axis (SA) running perpendicularly to the workpiece axis and to the pressure-exerting direction;
   wherein a controller of the device is configured such that a pivoting position of the finishing tool is controlled in dependence on an axial position of the linear movement such that
   in an end phase of a linear stroke, a leading, front end portion of the finishing tool, as seen in the movement direction of the linear movement, is located closer to the workpiece axis, and/or is pressed onto the circumferential surface by way of a higher local pressure-exerting force, than a trailing, rear end portion, wherein the finish-machining generates, by varying a surface-line shape which results from prior machining, a circumferential portion which has a fully crowned, a cylindrical crowned or a cylindrical logarithmic axial geometry.
4. Device according to claim 3, characterized in that the rotary axis is a machine axis.
5. Device according to claim 3 or 4, characterized in that the translatory machine axis (LA) has a horizontal slide (420), which is guided along horizontal guide rails (425), and in that the slide (420) bears the rotary machine axis, which comprises a rotary table (430) which can be rotated relative to the slide (420), with the aid of a numerically controlled rotary drive, about a horizontal axis of rotation, which corresponds to the pivot axis (SA).
6. Device according to claim 5, characterized in that the rotary table (430) bears a stone guide (440), which has a translatory machine axis in order to displace the tool holder (180) along an advancement direction which runs perpendicularly to the pivot axis (SA) and corresponds to the pressure-exerting direction (AR).
7. Device according to claim 6, characterized in that the rotary axis is an axis integrated in the finishing tool (500).

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