GB2494494A - Clamping device for machining a wheel flange unit - Google Patents

Abstract

The clamping device 1 is for running a machining operation on a wheel flange unit 4 with a wheel bearing in a processing machine. The device includes a holding unit for securing the wheel bearing outer ring 9 relative to the processing machine during the machining operation. The clamping device also has an aligning unit 10, 11 for temporarily securing the bearing inner ring 9 in an aligned position parallel with a tool feed plane 22 of the processing machine. The holding unit includes a wheel support 2 connected to the bearing outer ring 9 and a clamping arrangement 3 for variably clamping the wheel support so that it corresponds to the aligned position of the wheel bearing inner ring. The device enables wheel flanges with milled plane surfaces 6, 7 to be produced which - when fitted to a vehicle - have a true running defect of less than 20 micrometers i.e. they have less eccentricity or axial runout. As result, a vibration-free revolution of the wheel is possible and the braking behaviour of a disc brake is improved.

Description

Wheel flange unit and device and method of machining a wheel flange unit The invention relates to a clamping device for a processing machine and a method of running a machining operation on a wheel flange unit, as well as an associated wheel flange unit.

Wheel flange units comprising a wheel flange for accommodating a brake disc and/or a vehicle wheel and an associated wheel bearing as well as methods and devices used for machining flanges are known in principle from the prior art. In particular, wheel flange units of the generic type can be fitted on a wheel support, which is in turn connected to a chassis by means of wheel control arms and thus forms a part of the axle or wheel suspension of an automotive vehicle, for example.

In the case of wheel flange units of this type, it is necessary -to prevent vibrations in the axle system and in the steering of the motor vehicle -for the vehicle wheel to be mounted on the wheel flange so that it runs as exactly true as possible, especially as regards axial runout. This is particularly the case if the wheel is provided with a disc brake because any axial runout of the wheel flange is also transmitted to the brake disc, which can lead to vibrations and/or to uneven wear of the brake during braking. This can have a detrimental effect on both driving comfort and driving and braking safety.

An approach known from the prior art, for example from WO 00/74883 Ai, is to clamp a wheel flange unit comprising a wheel flange and a wheel bearing on the outer ring of the bearing, then displace the wheel flange in rotation about the axis of the wheel bearing and machine in particular the plane surface that will subsequently be used to accommodate the brake disc whilst the wheel bearing is rotating.

The intention is to remove and thus eliminate in this manner inaccuracies of both the wheel bearing and the connection between the wheel flange and wheel bearing as well as inaccuracies of the wheel flange itself, which could otherwise contribute to a significant eccentricity or axial runout, by means of the machining operation whilst rotating about the wheel bearing.

In the prior art, this machining of the wheel flange is usually done on a lathe.

However, this requires special machining tools on the one hand and on the other hand the task of loading and unloading is more complex in the case of a lathe than it is with a machining centre. Moreover, with the method known from the prior art, the clamping of the bearing outer ring does not correspond to the subsequent actual assembled situation of the wheel bearing in the wheel support, either in terms of the seating of the bearing in the wheel support or as regards the axial pre-tensioning of the flange and bearing inner ring. Furthermore, during subsequent assembly of a wheel flange unit fully machined in this way in the co-operating wheel support, deformations occur again in the wheel support, wheel bearing and/or wheel flange, which can therefore lead to exacerbated eccentricity or axial runout on the fitted wheel flange again.

Against this background, the objective of this invention is to propose a clamping device for a processing machine and a method of machining a wheel flange unit, as well as a wheel flange unit which enable these problems of the prior art to be overcome. In particular, the invention should enable the plane surface or brake disc mount of the wheel flange to exhibit only the slightest possible out of true running and to do so not only immediately after machining but also reliably in the final assembled state on the vehicle.

This objective is achieved by a clamping device as defined in claim 1, a method as defined in claim 12 and a wheel flange unit with the feature defined in claim 16.

Preferred embodiments constitute the subject matter of the dependent claims.

The clamping device is used for running a machining operation on a wheel flange of a wheel flange unit in a processing machine, and the processing machine comprises a machine frame and at least one tool feed plane in which machining of the wheel flange takes place. The wheel flange unit comprises a wheel bearing with a bearing inner ring and bearing outer ring as well as a wheel flange connected to the inner ring. The clamping device comprises a holding unit for securing the bearing outer ring relative to the processing machine during the machining operation. The machining operation takes place in a tool feed plane parallel with the machining surface of the wheel flange and perpendicular to the axis of the wheel bearing and whilst the wheel flange and bearing inner ring are rotating about the axis of the wheel bearing so as to thus eliminate out of true running and eccentricity of the wheel bearing and of the connection between the wheel flange and bearing inner ring.

As a result of the invention, the clamping device is improved due to the fact that it has an aligning unit for temporarily securing the bearing inner ring in an aligned position. In the aligned position, the bearing inner ring is aligned exactly parallel with the tool feed plane by means of the aligning unit. The holding unit of the clamping device further comprises a vehicle wheel support connected to the bearing outer ring and a clamping arrangement by means of which the wheel support can be variably clamped relative to the processing machine respectively in the retained position corresponding to the aligned position of the bearing inner ring which was fixed by means of the aligning unit.

Alignment of the bearing inner ring "parallel with the tool feed plane" within the meaning of the invention should be understood as meaning that the plane of symmetry (or an end face) of the bearing inner ring in this aligned position is aligned parallel with the plane (= tool feed plane) in which the relative movement takes place between the machining tool and the plane surface on the wheel flange to be machined.

In this respect, the relative movement between the machining tool and wheel flange (in addition to the rotation of the wheel flange about the wheel bearing which takes place in every case) may be obtained by moving either the machining tool or the clamping device (with the wheel flange unit clamped in it) relative to the machine frame. A movement of both the machining tool and the clamping device relative to the machine frame would also fall within the scope of the invention.

The expression "temporarily securing" the bearing inner ring in the aligned position within the meaning of the invention should be understood as meaning that the bearing inner ring is secured in the aligned position by means of the aligning unit is on a temporary basis only and is necessary until the holding unit, the wheel support and the wheel flange unit held in it have been clamped by means of the clamping arrangement relative to the processing machine in the relative position (determined by the aligning unit) with respect to the tool feed plane.

The expression "variably clamping" the wheel support relative to the processing machine by the clamping arrangement within the meaning of the invention should be understood as meaning that the clamping arrangement is set up so that the wheel support can be secured and clamped -within a limited range -by the clamping arrangement in any different (=variable) relative position relative to the processing machine. Accordingly, the respective relative position between the wheel support clamped in this manner and the processing machine corresponds to the relative position previously determined by the aligning unit, in other words the position resulting from the parallel alignment between the bearing inner ring and tool feed plane (due to the operating chain "aligning unit-> bearing inner ring -> bearing outer ring -> wheel support").

In other words, the clamping device enables the wheel flange to be machined and the co-operating wheel bearing to be assembled, before the final machining already, in the wheel support which will subsequently actually support the wheel bearing and wheel flange on the finished vehicle. Accordingly, the machining operation of the wheel flange takes place in the final assembled position of the wheel flange and wheel bearing in the wheel support itself.

To this end -by means of the aligning unit -the entire assembled unit comprising wheel support, wheel bearing and wheel flange is firstly aligned in the position in which the wheel bearing (or bearing inner ring) is positioned exactly parallel with the tool feed plane. Only then is the wheel support -with the bearing inner ring in exactly this aligned position -clamped relative to the processing machine. In other words, the wheel support (with the wheel flange unit already fitted in it) itself constitutes the clamping hold in which (whilst rotating the wheel flange about the wheel bearing) the machining operation of the wheel flange then takes place. In this respect, however, the position and alignment of the axis of rotation of the wheel bearing are not defined on the basis of the clamped position of the wheel support but rather the reverse is true and the clamped position of the wheel support is adapted to the position and alignment of the bearing inner ring -previously fixed by the aligning unit -and hence also the axis of rotation of the wheel bearing.

The out of true running and eccentricity associated with the clamping devices and methods of machining wheel flanges known from the prior art, which occur in particular due to the fact that, based on the prior art, the wheel flange unit is firstly clamped in a processing machine, machined there and then removed from the machine clamp again and finally fitted in a wheel support, are completely eliminated as a result of the invention.

The invention achieves this due to the fact that firstly, the wheel support itself is used as a holding unit for clamping the wheel bearing and the wheel flange to be machined, as a result of which the out of true running and eccentricity which occur otherwise during subsequent assembly of the wheel flange unit and wheel support are eliminated. Secondly, the accuracy achieved as a result of the invention when machining the wheel flange is particularly high, the reason being that in this instance, it is not the wheel support -potentially harbouring inaccuracies -serving as a clamping means which defines the machining position of the wheel flange unit.

Instead, due to the invention, it is conversely the wheel flange unit (or bearing inner ring) which initially determines the position in which the wheel support is then aligned relative to the processing machine and clamped, thereby eliminating all inaccuracies and tolerances of the wheel support as well.

In this manner, tolerances can be achieved -especially with regard to true running on the wheel flange -as a result of the invention and due to the clamping device, which are lower by up to a factor than the accuracies obtained by the devices and methods known from the prior art in terms of true running, with the corresponding advantageous effects in terms of the concentricity and true running of the wheels and in particular the brake discs of an automotive vehicle.

Based on a preferred embodiment of the invention, the aligning unit comprises an aligning element with an aligning surface, and the aligning surface can be positioned parallel with the tool feed plane. The aligning element is therefore set up so as to secure the bearing inner ring in the alignment position so that an end face of the bearing inner ring can be placed on and in contact with the aligning surface of the aligning element. In this respect, the clamping device has a clamping unit which is set up to clamp the wheel flange and bearing inner ring.

As a result of the aligning unit, the bearing inner ring and hence also the entire unit comprising the wheel flange, wheel bearing and wheel support can be moved exactly into the desired machining position -by means of the contact with the aligning surface of the aligning unit -in which the wheel support is then secured by means of the clamping arrangement, and in which the machining operation of the plane surface of the wheel support in particular takes place.

As a result of the clamping unit, an axial clamping of the wheel support and wheel bearing can also be achieved which matches the axial clamping of the wheel support and wheel bearing which actually exists subsequently on the vehicle in terms of the clamping force applied. This means that the same clamping conditions and hence elastic deformations prevail during machining of the wheel flange using the clamping device as those which prevail subsequently in the situation where the wheel flange unit is fitted on the vehicle. This results in a further improvement of the accuracy during the machining operation of the wheel support.

In this respect, the clamping unit preferably has a hydraulically releasable plate spring packet for clamping the wheel flange and bearing inner ring. The advantage of a plate spring packet is that a high axial force can be generated in a compact space and it therefore lends itself well to generating the high axial forces corresponding to those subsequently prevailing on the vehicle in the situation where the wheel bearing is fitted in the wheel support. The advantage of being able to release the plate spring packet of the clamping unit hydraulically is that the hydraulic pressure is applied only to release the clamping unit (during loading and unloading of the clamping unit), whereas the actual operation of machining the wheel flange can take place under a constant spring force of the plate spring packet and without the need to supply hydraulic pressure.

Based on another preferred embodiment of the invention, the clamping device has a support unit connected to the machine frame in a defined position. The support unit is used as a means of (temporarily) exactly supporting and hence securing the aligning unit in the relative position with respect to the processing machine corresponding to the subsequent aligned position of the wheel bearing, wheel flange and wheel support. The support unit therefore temporarily aligns the aligning unit so that the aligning surface of the aligning unit is aligned exactly parallel with the tool feed plane. Due to the fact that the clamping device is connected to the machine frame in a defined manner, the (known) position of the tool feed plane (relative to the machine frame) is therefore transmitted via the aligning unit to the support unit. In other words, the aligning unit can be (temporarily) positioned by means of the aligning unit so that the aligning surface of the aligning unit is aligned exactly parallel with the tool feed plane.

In this respect, the clamping unit is set up not only to clamp the wheel flange and bearing inner ring but to clamp both the wheel flange, bearing inner ring and the aligning unit. The latter means that when clamping the wheel flange to be machined to the bearing inner ring, the aligning unit is also clamped to the bearing inner ring in addition. The operation of machining the wheel flange therefore takes place whilst the rigidly clamped unit comprising the wheel flange, bearing inner ring and aligning unit rotate jointly. Due to the fact that the bearing inner ring is clamped not only to the wheel flange but also to the aligning unit, a reliable, fixed and exact abutment is initially obtained between the bearing inner ring and aligning surface on the aligning unit when the bearing inner ring is being aligned by means of the aligning unit.

Due to the fact that the support unit connected to the machine frame secures the aligning unit only temporarily (and does so until the aligning unit, bearing inner ring and wheel flange have been clamped by the clamping unit), an unhindered free rotation of the wheel flange and bearing inner ring -including the aligning unit clamped to the bearing inner ring -is also guaranteed about the actual axis of the wheel bearing during the operation of machining the wheel flange.

It is only the free and unhindered (in particular by the support unit) rotation of the wheel flange about the actual axis of the wheel bearing (including its variances from concentricity and true running) obtained as a result which guarantees that the effects of these variances from concentricity and true running of the wheel flange can be completely removed and hence eliminated whilst it is being machined.

Initially, it is irrelevant how the aligning unit is (temporarily) supported by the support unit, as long as the exact positioning of the aligning unit is guaranteed, without clearance, relative to the support unit (and hence relative to the machine frame and relative to the tool feed plane). Based on a preferred embodiment, however, the aligning unit is secured by means of a centring unit, and the centring unit has a plurality of (preferably three) radial pistons. Using three radial pistons in particular enables a positioning and securing of the aligning unit to be obtained relative to the support unit that is statically neither under-defined nor over-defined and hence exact, which is also conducive to the high accuracy of the subsequent machining operation of the wheel flange.

Based on another preferred embodiment, the clamping unit has an annular piston disposed coaxially with the axis of rotation of the wheel bearing, with an end-face operating chamfer, whilst the radial pistons respectively have an operating bevel against which the operating chamfer of the annular piston is slidingly moved into abutment. In this manner, the radial pistons can be operated simultaneously and in an exactly svnchronised manner in terms of the movement of the radial pistons by means of the operating chamfer of the annular piston-It is of advantage to use an annular piston because other components of the clamping device can be disposed in the free interior of the annular piston, in particular the clamping unit and its preferably hydraulic operating system and supply.

The invention can be implemented irrespective of what tool type is selected and how the machining operation of the wheel flange takes place, including on a lathe for example. However, the processing machine in which the clamping device can be used preferably has a device for running a milling operation on the wheel flange, and the milling operation takes place along the tool feed plane in particular. The clamping device preferably has a drive unit for driving the wheel flange unit in rotation during the machining, in particular milling, operation In this manner, not only can the clamping device proposed by the invention be used in lathes but also in CNC machining centres, in which the tool machining takes place by means of a milling head, in particular a face cutter. It is of advantage to machine the wheel flange by milling in a processing centre rather than by truing in a lathe (as is usually the case in the prior art), firstly because the special machining tools needed (if using a lathe) can be dispensed with as a result and secondly because the workpiece can be loaded and unloaded more easily and quickly in a machining centre compared with a lathe. Due to the fact that the wheel flange can be displaced in rotation -by means of the drive unit for driving the wheel flange unit in rotation -about the axis of the wheel bearing during the milling operation, there is also no need for any further relative movement between the wheel flange and the milling head (apart from the relative feeding movement between the wheel flange unit to be machined and the milling head along the at least one tool feed plane). Consequently, eccentricity and true running defects of the unit comprising the wheel bearing and wheel flange are reliably removed and eliminated during the milling operation.

With regard to the rotary drive of the wheel flange unit during the milling operation, it is of advantage and specifically provided in the case of another embodiment of the clamping device that the drive unit has a coupling unit to provide an elastic rotary coupling between the drive unit and the aligning unit. In this connection, there is also a radial and/or axial clearance between the aligning unit and the support unit. This being the case, the wheel flange unit can be driven in rotation for the milling operation of the wheel flange without the free rotation of the wheel flange and bearing inner ring about the bearing axis of the wheel bearing being impeded -for example by the drive unit of the clamping device. This ensures that the rotation of the wheel flange in particular is actually effected about the axis of the wheel bearing (which might have concentricity or true running defects), as a result of which the effects of any concentricity or true running defects of the wheel bearing on the concentricity and true running of the wheel flange can be removed and thus eliminated.

The invention further relates to a method of running a machining operation on a wheel flange of a wheel flange unit in a processing machine. The wheel flange unit comprises a wheel bearing with an inner ring and outer ring as well as a wheel flange connected to the inner ring. The wheel flange unit is also already integrated in a wheel support and the processing machine comprises a machine frame, a tool for the machining operation on the wheel flange, (at least) one tool feed plane and a clamping device with an aligning unit, clamping unit and support unit as described above. The method comprises the method steps set out below.

Firsfly, in a method step a), the wheel support with the wheel flange unit integrated in it is placed in the clamping device.

Then, in a method step b), the bearing inner ring is laid on the aligning unit. At this stage, the aligning unit is secured by means of the support unit in the aligned position (relative to the clamping device and to the machine frame of the processing machine) in which the aligning unit for the bearing inner ring is aligned parallel with the tool feed plane.

In another method step c), the wheel flange, bearing inner ring and aligning unit are then clamped by means of the clamping unit of the clamping device. As a result, the wheel support is aligned (based on the component chain "machine frame/clamping device -> support unit -> aligning unit -> bearing inner ring -> bearing outer ring -> wheel support") corresponding to the aligned position of the aligning unit, which is in turn imparted to the aligning unit by the support unit (connected to the machine frame).

In method step c), therefore, the wheel support respectively assumes the relative position with respect to the machine frame corresponding to the parallel alignment of the inner ring of the wheel bearing with the tool feed plane, and this relative position of the wheel support will be different depending on the tolerances and inaccuracies which exist on the wheel flange unit or on the wheel support.

In a method step d), the wheel support is then clamped in the relative position (previously fixed by the aligning unit 10, ii) relative to the machine frame. In method step d), therefore, the wheel flange and the wheel flange unit disposed in it are secured so that the inner ring of the wheel bearing will maintain the parallel alignment with the tool feed plane imparted to it in method steps b) respectively c) even if the connection between the aligning unit and support unit is then established separately, as happens in method step e).

Finally, in another method step f), the wheel flange unit is driven in rotation by the clamping device (or by the processing machine). Accordingly, the machining operation of the wheel flange takes place as the wheel flange and bearing inner ring rotate about the axis of the wheel bearing.

The method therefore ensures that the machining operation, which takes place in the tool feed plane and with the wheel flange simultaneously rotating about the axis of rotation of the wheel bearing based on the method, and with the wheel bearing aligned parallel with the tool feed plane, is implemented with the highest degree of accuracy, especially with respect to the true running of the surface or surfaces on the wheel flange to be machined.

In principle, the method can be initially implemented regardless of the type of processing machine used, including on a lathe for example. However, the processing machine preferably has a milling unit, which can be displaced relative to the workpiece in the tool feed plane, and in order to implement the relative movement within the meaning of the invention, either the milling unit or the workpiece or both can be moved. Accordingly, in method step 0, a milling operation of the wheel flange takes place in and along the tool feed plane.

This embodiment is of advantage because the wheel flange can therefore be machined in a milling machine or in a machining centre. This obviates the need for special tools such as used with a lathe and hence the associated high tool costs. At the same time, due to the possibility of being able to use a machining centre, the process of loading and unloading the wheel flange unit is made easier than it would be with a lathe, thus resulting in advantages as regards cycle times and other cost advantages.

Based on another preferred embodiment of the method, the machining operation of the wheel flange in method step f) takes place with wheel bolts already pressed into the wheel flange. By pressing wheel bolts into the wheel flange, the latter is usually deformed not only plastically as well as elastically in the region incorporating the wheel bolts, but in addition a different clamping profile from that of the initial state is also imparted to it, which in turn results in higher tolerances or deflections even if the wheel flange is running true.

By machining the wheel flange with wheel bolts already pressed in, based on the subject matter of this embodiment of the method, the plastic and elastic deformations which occur in the wheel flange as the wheel bolts are pressed in can also be eliminated. This embodiment therefore also results in an extremely low variance from true running of the wheel flange unit during service -fitted on the vehicle.

Another particularly preferred embodiment of the method is distinctive due to the fact that the rotary driving movement of the wheel flange unit takes place by means of an elastic rotary coupling between a rotary drive unit of the clamping device (or processing machine) and the aligning unit.

This embodiment enables as free a rotation as possible of the wheel flange about the axis of rotation of the wheel bearing even if the wheel flange, bearing inner ring and aligning unit are clamped together by means of the clamping unit, as is the case in method steps c) toO. In other words, if the wheel bearing exhibits inaccuracies with regard to its axis of rotation, the unit (connected in a clamped arrangement by the clamping unit) comprising the wheel flange, bearing inner ring, aligning unit and clamping unit, are also then able to rotate freely about the axis of rotation of the wheel bearing if the latter deviates slightly from the axis of rotation of the machine drive unit in terms of position and/or angle as a result of the elastic rotary coupling between the drive unit and aligning unit.

The invention further relates to a wheel flange unit for an automotive vehicle.

The wheel flange unit is integrated in a wheel support, comprises a wheel flange and wheel bearing, and is distinctive due to the fact that -in the state fitted on the wheel support or automotive vehicle -there is a milled plane surface with a true running defect of less than 20 rim on the wheel flange. The plane surface on the wheel flange is created or can be created by means of a processing machine and the clamping device described above and by means of a processing method of the type described above based on milling.

As a result of the invention, the wheel flange therefore has -in the state fitted on the vehicle and in the wheel support -a true running defect that is smaller than that achieved by the prior art to date by a factor of five. In addition, the surfaces to be machined on the wheel flange can be created to the specified accuracy by means of a milling operation (preferably with a face cutter) for the first time, saving on time and costs, and thus in a known manner using milling tracks extending in a circular arrangement, e.g. by means of a face cutter on the contact surfaces for the wheel and the brake disc on the wheel support.

The invention will be described in more detail below with reference to the drawings illustrating what are merely examples of embodiments. Of these: Fig. i: is an isometric diagram illustrating an embodiment of a clamping device based on the invention with a clamped-in wheel support; and Fig. 2: is a side view of the clamping device illustrated in Fig. 1 in partial section.

Fig. i illustrates an embodiment of a clamping device i based on the invention.

A wheel support 2 for an automotive vehicle is clamped into the clamping device i.

Having an appropriate number of straps 3, the clamping device i illustrated is suitable both for right-hand and left-hand wheel supports 2 of an axle, which usually have the same geometry in minor image.

A wheel flange nnit 4 with a wheel flange 5 is already integrated in the wheel support 2. The wheel flange 5 illustrated has two plane surfaces 6, 7, against which co-operating contact surfaces of a brake disc will subsequently sit in contact when on the vehicle. As a result, a great deal of importance is attached to the exact true running of the plane surfaces 6, 7 of the wheel flange 5 -in particular with regard to safe and vibration-free operation of the disc brake of the automotive vehicle.

As may also be seen from Fig. i, wheel bolts 8 have already been inserted in the wheel flange 5, for example pressed in. Since the wheel flange 5, including its plane surfaces 6, 7, are usually both plastically and elastically deformed as wheel bolts 8 are pressed in, it is of considerable importance that the wheel bolts 8 are pressed in before the machining operation of the plane surfaces 6, 7. If, as illustrated, the machining operation of the plane surfaces 6, 7 of the wheel flange is run with wheel bolts 8 already pressed in, the plastic and elastic deformations of the plane surfaces 6, 7 of the wheel flange which occur when the wheel bolts are being pressed in are removed again by the machining operation of the plane surfaces 6, 7 and are thus eliminated in terms of the possible detrimental effect they would otherwise have on the true running of the brake disc.

The machining operation of the plane surfaces 6, 7 of the wheel flange 5 is run by means of a processing machine (not illustrated) with a milling head whilst simultaneously rotating the wheel flange 5 about the axis of rotation (not visible in Fig. i) of the wheel bearing, the outer ring of which has been pressed into the wheel support 2, whilst the inner ring accommodates the wheel flange 5. Accordingly, the milling head is fed relative to the wheel flange unit 4 into the machining position by a relative movement between the milling head and machine bench or clamping device 1 in the radial and optionally axial direction with respect to the wheel flange 5, whilst the actual removal of material from the plane surfaces 6, takes place solely by rotating the wheel flange about the axis of rotation of the wheel bearing.

Since the machining operation of the plane surfaces 6, 7 of the wheel flanges can therefore be implemented in the state in which the wheel flange j is fitted -including the wheel bolts 8, wheel bearing and wheel support 2 -as result of the invention, with the actual axis of rotation of the wheel bearing (and not an axis of rotation of the processing machine or clamping device) defining the plane where the material is removed, an exact milling of the plane surfaces 6, 7 of the wheel flange 5 can be specifically obtained due to the invention that has not been achievable to date.

Accordingly, not only are the plastic and/or elastic deformations of the wheel flange which occur when the wheel bolts 8 are pushed in eliminated, but also the deformations and inaccuracies which occur during assembly of the bearing outer ring in the wheel support 2 and or during assembly of the wheel flange j and bearing inner ring, as well as any concentricity or true running defects of the wheel bearing itself.

Fig. 2 illustrates the clamping device 1 illustrated in Fig. 1 but in a diagram from the side in partial section. The wheel support 2 may be seen, partially indicated by broken lines in Fig. 2, because the diagram of the wheel support 2 in this instance shows a right-hand and left-hand wheel support superimposed in order to demonstrate that both the right-hand and left-hand wheel support can be clamped in one and the same clamping device 1. Also illustrated (shown in partial section), is the wheel flange 5 with wheel bolts 8 pressed in as well as its seating in the inner ring g of the wheel bearing 9, 9'.

The outer ring 9' of the wheel bearing has already been fitted in the co-operating recess of the wheel support 2 in the final position (corresponding to subsequent use in the automotive vehicle).

Fig. 2 also shows the aligning unit 10, 11, which is used as a means of obtaining an exactly vertical alignment of the axis of rotation of the wheel bearing 9, 9' -prior to clamping the wheel support 2 in the clamping device 1. To this end, the aligning unit 10, ii comprises what in the embodiment illustrated is a pot-shaped aligning element with a stop ring ii. The clamping device 1 also has a clamping unit 12, 13, 14, i5with a hydraulic piston 12, a plate spring arrangement 13, a piston rod 14 and a clamping nut i. The hydraulic piston 12 is connected to the piston rod 14, onto which the clamping nut 15 is screwed.

As long as hydraulic liquid pressure is applied to the cylinder chamber (underneath the piston 12 by reference to the drawing) by means of the supply line i6, the piston 12 presses the plate spring arrangement 13 together and the piston rod 14 is disposed in its top end position by reference to the drawing. When the piston rod is in this position, the wheel support 2 with the wheel flange unit 4 already fitted -in this instance comprising the wheel flange, wheel bolts 8 and wheel bearing 9, 9' -can be placed in the clamping device 1.

As the wheel support 2 with the wheel flange unit 4is inserted, the bearing inner ring 9 of the wheel bearing is moved so that it lies on the flat surface of the stop ring ii of the aligning unit 10, 11, and the stop ring 11 is supported by the aligning element 10.

As the wheel support 2 is being inserted and then clamped, the aligning unit 10, 11 is also fixedly connected to the base plate 17 of the clamping device 1 by means of a support unit i8, 19, 20, 21. To this end, the support unit i8, 19, 20, 21 has a hydraulically operable annular piston i8, which has circumferentially extending annular chamfer 19. The annular chafer 19 is used as a means of operating, in a direction directed radially inwards, three radial pistons 20 distributed uniformly along the circumference of the aligning element 10 which are disposed in a radially sliding arrangement in a supporting sleeve 21 connected to the base plate 17 of the clamping device 1. Only one radial piston 20 of the three radial pistons 20 is visible (due to the position of the section plane in Fig. 2).

The radial pistons 20 are therefore forced radially inwards -due to the axial movement of the annular piston i8 upwards by reference to the drawing and the sliding of the annular chamfer 19 of the annular piston i8 on co-operating operating bevels of the radial pistons 20. By means of the operating chain "base plate 17-> support sleeve 21 -> radial pistons 20 -> aligning element 10", this causes the aligning unit 10, ii to be (temporarily) secured relative to the base plate 17. This imparts to both the aligning element 10 and the stop ring 11 an exactly parallel or horizontal alignment relative to the base plate 17 and hence to the machine frame, which is in turn likewise aligned parallel with the tool feed plane 22 during the subsequent machining of the wheel flange 5 in the processing machine (not illustrated).

In other words, what is effectively the top surface of the stop ring ii by reference to the drawing is thus initially aligned exactly horizontal (or exactly parallel) with the subsequent tool feed plane 22. When the wheel support 2 is inserted via the operating chain "stop ring 11 -> wheel bearing 9, 9' -> wheel bearing seat -> wheel support 2", this alignment is then also imparted to the wheel support 2.

Once the wheel support 2 has been inserted, the clamping nut 15 is loosely screwed onto the piston rod 14, after which the hydraulic pressure in the line 16 is deactivated. As a result -due to the then expanding plate spring packet 13 -the wheel flange unit and aligning unit io, ii are clamped along the now closed operating chain "plate spring packet 13 -> piston rod 14 -> clamping nut 15 -> wheel flange s -> bearing inner ring -> aligning element 10 -> piston 12".

In this manner, the wheel support 2 is therefore aligned exactly in the relative position with respect to the base plate 17 corresponding to the parallel alignment of the bearing inner ring 9 relative to the base plate 17 and relative to the tool feed plane 22 of the processing machine. In this relative position (which may turn out to be slightly different with every wheel support to be clamped in or by every wheel flange unit to be machined due to the different tolerances and inaccuracies of the wheel bearing 9, 9', wheel support 2 and wheel support bearing seat), the wheel support is then initially supported by support punches -which can be hydraulically fixed at a variable height for example. The wheel support 2 is then clamped by the straps 3 against the support punches which are then rigidly connected (not visible in the drawings because they are covered) and thus secured relative to the base plate 17.

Once the wheel support 2 with the wheel flange unit, 8, 9, 9' accommodated in it has been clamped in this manner respectively in the relative position with respect to the base plate 17 corresponding to the exactly parallel alignment of the bearing inner ring 9 with the tool feed plane 22, the clamped connection between the support unit i8, 19, 20, 21 and aligning unit 10, ii is released by hydraulically discharging and hence axially moving the annular piston i8 downwards by reference to the drawing, and due to the radial movement of the radial pistons 20 outwards triggered as result.

This terminates the previous fixed connection between the support unit i8, 19, 20, 21 and aligning unit 10, 11 but the clamp between the aligning element 10, stop ring ii, bearing inner ring 9 and wheel flange 5 continues to be maintained (including during the subsequent process of machining the plane surfaces 6, 7 of the wheel flange 5).

The fact of clamping the bearing inner ring 9 and wheel flange 5 by means of the plate spring packet 13 -during the machining operation of the plane surfaces 6, 7 of the wheel flange 5 -is of importance insofar as it reproduces the subsequent clamping of the bearing inner ring 9 and wheel flange 5 (due to being screwed to the vehicle drive shaft, typically with an axial pre-tensioning in the order of ca. 100 kN) in the actual state in which the wheel support 2 and wheel flange unit 4 are fitted on the vehicle. This means that, in terms of the clamp between the wheel flange 5 and bearing inner ring 9, exactly the clamping conditions and hence elastic deformations already prevail between the wheel flange 5 and the bearing inner ring 9 during the machining operation of the plane surfaces 6, 7 of the wheel flange 5 as those which actually occur in the state subsequently fitted on the vehicle. The effects of these deformations can therefore also be eliminated already during the machining operation of the plane surfaces 6, 7 of the wheel flange 5 due to the fact that the wheel flange 5 having these deformations can be machined flat again along the tool feed plane 22 during the machining operation already.

In order to minimise the effects of the drive unit -clamped by the plate spring packet 13 -for driving the unit comprising the wheel flange 5, bearing inner ring 9 and aligning element 10 in rotation during the machining operation, the torque is transmitted to the aligning unit 10, 11 (and hence to the bearing inner ring 9 and wheel flange 5) via a cardanically elastic coupling with coupling pins 23. The coupling pins 23 transmit the driving torque from a hollow shaft 24 -driven in rotation by the processing machine -to a coupling plate 25, and the coupling pins 23 do not locate in the coupling plate 25 directly but rather via elastomer inserts. The coupling plate 25 is in turn rigidly connected to the aligning element 10 (and thus simultaneously forms the cylinder chamber for the hydraulic piston 12). Due to the rigid connection between the coupling plate 25 and the aligning element 10, the rotating movement transmitted by the driven hollow shaft 24 via the elastic coupling 23 is transmitted to the aligning element 10 and hence also to the bearing inner ring 9 and wheel flanges because they are clamped to the aligning element in by means of the clamping unit 12, 13, 14, 15.

Accordingly, the wheel flange is therefore able to rotate exactly about the axis of rotation of the wheel bearing 9, 9' itself during the machining operation, even if it deviates slightly in terms of position and/or angle from the axis of rotation of the drive unit 23, 24 of the clamping device (or processing machine). Slight radial and or axial relative movements which occur as a result between the aligning element 10 (rotating with the wheel flange about the axis of rotation of the wheel bearing 9) and the support unit i8, 19, 20, 21 are therefore possible but largely free of any reaction force -due to a radial and/or axial clearance provided accordingly between the aligning element 10 and support sleeve 21. This also contributes to a further improvement to accuracy during the machining operation of the plane surfaces 6, 7 of the wheel flange 5.

Reference numbers i Clamping device 2 Wheel support 3 Clamping strap 4 Wheel flange unit Wheel flange 6, 7 Plane surfaces 8 Wheel bolts g Bearing inner ring 9 Bearing outer ring Aligning element 11 Stop ring, aligning surface 12 Hydraulic piston 13 Plate spring packet 14 Piston rod Clamping nut i6 Hydraulic supply line 17 Base plate iS Annular piston ig Annular chamfer Radial piston 21 Support sleeve 22 Tool feed plane 23 Coupling pin 24 Drive hollow shaft Coupling plate

Claims (1)

1. <claim-text>Claims i. Clamping device (i) for running a machining operation on a wheel flange () of a wheel flange unit (4) in a processing machine, the wheel flange unit () comprising a wheel bearing with an inner ring (9) and outer ring (s') as well as a wheel flange () connected to the inner ring (cj), the clamping device (i) comprising a holding unit for securing the bearing outer ring (s') relative to the processing machine during the machining operation, which takes place in a tool feed plane (22) of the processing machine lying parallel with the wheel flange and perpendicular to the longitudinal axis of the wheel bearing whilst rotating the wheel flange (s) and bearing inner ring () about the axis of the wheel bearing (9, 9'), characterised in that the clamping device (i) has an aligning unit (io, ii) which is set up to temporarily secure the bearing inner ring (9) in an aligned position in which the bearing inner ring () is aligned parallel with the tool feed plane (22) by means of the aligning unit (in, ii), and the holding unit has a wheel support (2) connected to the bearing outer ring (9') and a clamping arrangement () which is set up to variably clamp the wheel support (2) relative to the processing machine respectively in the holding position corresponding to the aligned position of the bearing inner ring (9) fixed by means of the aligning unit (io, ii).</claim-text> <claim-text>2. Clamping device as claimed in claim 1, characterised in that the aligning unit (in, ii) comprises an aligning element (in) with an aligning surface (ii) which can be positioned parallel with the tool feed plane (22), and the aligning element (in) is set up to secure the bearing inner ring (ç) in the aligned position by means of an abutment of an end face of the bearing inner ring () on the aligning surface (ii).</claim-text> <claim-text>3. Clamping device as claimed in claim 1 or 2, characterised in that the clamping device (i) has a clamping unit (12, 13, 14, is), and the clamping unit (12, 13, 14, i) is set up to clamp the wheel flange () and bearing inner ring (p).</claim-text> <claim-text>4. Clamping device as claimed in claim 3, characterised in that the clamping unit (12, 13, 14, 15) has a hydraulically releasable plate spring packet (13) for clamping the wheel flange () and bearing inner ring ().</claim-text> <claim-text>5. Clamping device as claimed in one of claims 2 to 4, characterised in that the clamping device has a support unit (18, 19, 20, 21) connected to a machine frame of the processing machine in a defined manner which is set up to temporarily secure the aligning unit (io, ii) in an aligned position relative to the machine frame of the processing machine in which the aligning surface (io) of the aligning unit (io, ii) is aligned parallel with the tool feed plane (22) by means of the support unit (18, 19, 20, 21).</claim-text> <claim-text>6. Clamping device as claimed in claim, characterised in that the clamping unit (12, 13, 14, 15) is set up to clamp the wheel flange (s), bearing inner ring (9) and aligning unit (io, ii).</claim-text> <claim-text>7. Clamping device as claimed in claim or 6, characterised in that the aligning unit (to, ii) is secured by a centring unit (18, 19, 20) with a plurality of radial pistons (20).</claim-text> <claim-text>8. Clamping device as claimed in claim 7, characterised by an annular piston (18) disposed coaxially with the axis of rotation of the wheel bearing (ca, 9') with an end-face operating chamfer (19), and the radial pistons (20) respectively have an operating bevel for operating the radial pistons (20) against which the operating chamfer (19) of the annular piston (i8) lies in a sliding arrangement for simultaneously operating the radial pistons (20).</claim-text> <claim-text>9. Clamping device as claimed in one of claims 1 to 8, characterised in that the processing machine has a milling unit for running a milling operation on the wheel flange unit (4) along the tool feed plane (22).</claim-text> <claim-text>10. Clamping device as claimed in one of claims 1 to 9, characterised in that the clamping device has a drive unit (23, 24, 25) for driving the wheel flange unit () in rotation during the machining operation.</claim-text> <claim-text>11. Clamping device as claimed in claim 10, characterised in that the drive unit (23, 24, 25) has a coupling device (23, 25) for establishing an elastic rotary coupling with the aligning unit (io, ii), and a radial and/or axial clearance exists between the aligning unit (io, ii) and support unit (iS, 19, 20, 21).</claim-text> <claim-text>12. Method of running a machining operation on a wheel flange of a wheel flange unit () in a processing machine, the wheel flange unit (z) comprising a wheel bearing with an inner ring (9) and outer ring (s') as well as a wheel flange (5) connected to the inner ring (9), and the wheel flange unit () is integrated in a wheel support (2), the processing machine having a machine frame, a tool feed plane (22), a machining tool and a clamping device (i) with an aligning unit (to, ii), clamping unit (12, 13, 14, i) and support unit (18, 19, 20, 21) as claimed in one of claims 5 to 11, comprising the method steps a) inserting the wheel support (2) with the wheel flange unit () integrated in it in the clamping device (1); b) placing the bearing inner ring () in abutment with the aligning unit (to, ii), whereby the aligning unit (to, ii) is secured by means of the support unit (iS, 19, 20, 21) in an aligned position relative to the machine frame of the processing machine in which the aligning unit (to, ii) for the bearing inner ring (ca) is aligned parallel with the tool feed plane (22); c) clamping the wheel flange (s), bearing inner ring () and aligning unit (to, n) by means of the clamping unit (12, 13, 14, 15) whilst aligning the wheel support (2) so that it corresponds to the aligned position of the aligning unit (io, ii); d) clamping the wheel support (2) relative to the machine frame in the holding position which corresponds to the aligned position fixed by the aligning unit (in, ii) and bearing inner ring () in method steps b) and c); e) releasing the connection between the aligning unit (io, ii) and support unit (18, 19, 20, 21); 1) driving the wheel flange unit () in rotation and running a machining operation on the wheel flange (s) whilst rotating the wheel flange () and bearing inner ring @) about the axis of the wheel bearing (cj, 9').</claim-text> <claim-text>13. Method as claimed in claim 12, characterised in that the processing machine has a milling unit which can be relatively displaced in the tool feed plane (22), and a milling operation of the wheel flange () takes place within the tool feed plane (22) in method step 0.</claim-text> <claim-text>14. Method as claimed in claim 12 or 13, characterised in that the machining operation of the wheel flange () takes place with wheel bolts (8) pressed into the wheel flange (5).i. Method as claimed in one of claims 12 to 14, characterised in that the wheel flange unit () is driven in rotation by means of an elastic rotary coupling (23, 25) between a drive unit and the aligning unit (in, ii).16. Wheel flange unit () integrated in a wheel support (2) for an automotive vehicle, the wheel flange unit (zØ comprising a wheel flange (j) and a wheel bearing (ç, 9'), characterised in that the wheel flange unit (4) has a milled plane surface (6, 7) with a true running defect of less than 20 m on the wheel flange (s), and the wheel flange plane surface (6, 7) is created or can be created by milling by means of a processing machine and a clamping device (i) as claimed in one of claims 1 to 11 or by means of a machining method as claimed in one of claims 12 to i.</claim-text>