DE4339754C1 - Device for making bores in a dish or a rim of a motor-vehicle wheel - Google Patents

Abstract

The device serves to make bores in a wheel of a motor vehicle by means of a numerically controlled machining centre. The wheel is held in a clamping fixture which permits pivoting of the wheel about an axis (24) perpendicular to the wheel axis. The clamping fixture contains a pivot bearing on both sides of the wheel. The clamping fixture is designed as an indexing attachment (22). One of the pivot bearings is formed by a rotary device and the other pivot bearing is formed by a counter bearing (30) of the indexing attachment (22). The counter bearing (30) can be locked in the swivelling direction (Fig. 4). <IMAGE>

Description

The invention relates to a device for introducing Bores in a bowl or rim of a motor vehicle Wheel by means of a numerically controlled machining center, where the wheel is in an axis perpendicular to the wheel axis pivotable clamping device is held on both sides of the Rades includes a pivot bearing.  

A device of the aforementioned type is known from the DE-PS 37 35 858 known.

Devices of this type are used in large series production used by motor vehicle wheels. In the course of this production is it necessary within a processing section Make the necessary holes on the wheels. This are in particular the so-called mounting holes that provided for later attachment of the wheel to the motor vehicle are. The mounting holes are parallel to the wheel axis aligned. There is also at least one valve on each wheel hole arranged. The valve hole is used to push through the valve of the vehicle tire. During the attachment holes are usually arranged in the bowl of the wheel the valve bore is provided in the wheel rim. The The valve bore is inclined relative to the wheel axis.

Therefore, if you want to drill these holes in the wheel, you have to you tilt the wheel once because the holes are different are aligned and the drill in general with its Axis direction is fixed. One is therefore, for example, first Align the wheel horizontally and the mounting holes Attach using a vertical axis drill. The wheel will then tilted by the angle of inclination of the valve bore so that now the valve bore with a drill in the same direction can be attached.

In the course of the further development of such devices strived to reduce cycle times. So that goes Along with this, the feed speeds of the drills increase increase so that the total of the axial exerted on the wheel forces are also increasing.  

Already with the device according to the above DE-PS 37 35 858 are the wheels in their clamping devices stored on both sides, because a flying storage for such Eliminates use cases. In the known device two wheels side by side on a tandem clamping device arranged, which sits on a horizontal-axis swivel shaft. One engaging in the middle of the swivel shaft via a lever arm Actuating mechanism can now turn the swivel shaft around turn the angle of inclination of the valve bore so that the wheels are tilted between two end positions at which one the mounting holes and the other It is possible to attach the valve bore.

In certain applications, you would now like to instead of Special devices described above to standard use components, for example a dividing head. Dividers are aggregates with which it is possible, e.g. B. a workpiece by a predetermined precise angular step to twist in order to process steps on the perform turned workpiece. There are dividers known with which a workpiece can be clamped on the fly can, but there are also known sub-devices in which the Workpiece between a turning device and a counter bearing is clamped so that even greater radial forces (relative to the axis of rotation of the dividing head) can be intercepted.

If you have such a dividing head with counter bearing for clamping of a wheel in which mounting holes and valve bores should be attached, however, results in Another problem:  

Because the bores mentioned partially differ considerably from the wheel axle are spaced and can not be guaranteed that the Locations of these holes along the axis of rotation of the dividing head these locations can also be radial from the Place the axis of rotation of the dividing head. If now the drill Drilling creates the strong axial forces of the drill an additional torque about the axis of rotation, that of the axial force, multiplied by the distance of the drilling location from the axis of rotation of the dividing head.

Regarding the rotating device of the sub-apparatus itself this is not a problem because the turning devices in space common self-locking motors included or self-locking Motor-gear assemblies, so that the above Torque does not cause the motor to twist and therefore the Workpiece in the direction of rotation.

With conventional dividing heads, however, the counter bearing is free trained to rotate. It can therefore do so at high torques come that the wheel or the jig between Rotating device and counter bearing is clamped, are rotated. Since the clamping device only with conventional dividing heads could be clamped on one side of the rotating device, this could lead to noticeable errors.

The invention is therefore based on the object of a device of the type mentioned in such a way that with conventional units a tilting of the wheel for a Subsequent attachment of mounting holes and valve bores is possible without the occurrence of the torques and a twisting of the clamping device errors occur.  

This object is achieved in that the Clamping device is designed as a partial apparatus, one the swivel bearing has a positionable rotary drive and the other swivel bearing as a counter bearing in the swivel direction is lockable.

The object on which the invention is based is achieved in this way completely solved.

The use of a dividing head consisting of a rotating device and counter bearing, namely it initially allows commercially available Use units for pivoting the wheels, so that expensive Special devices are unnecessary. It will also be based on this Achieved greater flexibility because the following Editing series of different wheels also differed The angle of inclination of the valve bores must be taken into account can, by reversing the dividing head accordingly, what with special devices, for example according to the beginning mentioned type, is not easily possible.

The lockability of the counter bearing also has the advantage that a twisting of the clamping device by high, remote from the axis Drill forces not possible or only to a very limited extent is because the tensioning device acting as a torsion bar is now is clamped at both ends in a rotationally fixed manner.

In a preferred embodiment of the invention the counter bearing lockable by friction.  

This measure has the advantage that it is simple in construction is possible and the lock in any rotational position of the clamping device direction is possible because positive elements, for example wise gears, not be brought into engagement with each other have to.

Another embodiment of the invention is distinguished characterized in that the shaft of the counter bearing via a clamping is rotatably held in a housing of the counter bearing, and that friction elements in the radial direction on a peripheral surface the shaft can be applied.

This measure has the advantage that a simple constructive Construction is possible because the already existing wave in the Counter bearing with a peripheral surface to achieve the locking effect can be used.

It is preferred if the friction elements by means of a piston are operable.

It is also preferred in this case if the piston over an effective area with compressed air of a company compressed air systems can be operated.

It is further preferred in this case if the piston is a Has effective area which is dimensioned so that the friction elements with compressed air of a company compressed air system are operable.  

This measure has the advantage that there is no separate fluid source is required, in particular no leakage-prone Hydraulic device, but rather the already existing one company compressed air can be used. Because this compressed air with typically 8 bar operating pressure only on one relative low pressure, compared to conventional pressure operated Drives, the effective areas of the pistons must be correspondingly large dimension, which is interesting for aggregates here the species is possible.

In a further preferred variant of the invention there are two Friction elements can be actuated simultaneously by means of two pistons.

This measure has the advantage that the blocking effect is special can be reliably achieved because the blocking effect of the two pistons added.

It is particularly preferred if the pistons run in opposite directions is deflectable and by a common one, between the pistons arranged cylinder space can be acted upon.

This measure has the advantage that the blocking effect particularly easy way can be realized because for both Piston only a single, common pressure supply necessary is.

Furthermore, a good effect is achieved in that everyone Piston is guided on the shaft.

This measure also has the advantage of being particularly simple Construction because there is no need for a separate bearing for the pistons Lich, if these are designed as annular pistons, the run on the already existing wave.  

In this variant of the invention it is particularly preferred if each friction element is designed as a bellows-like locking element is that sits on the shaft and under axial load radially thickened and dense in a cylindrical bore held, on the one hand, to a housing-fixed radial Supporting surface supports and on the other hand rests on the piston.

This measure has the advantage that a very small distances very large blocking effect can be achieved. Furthermore, from Advantage that the bellows-like locking elements have a spring character ristik, so that after releasing the actuation pressure automatically reset and thus a relief from the opposite piston side is not required.

It is understood that the above and the following standing features to be explained not only in each specified combination, but also in other combinations or can be used alone, without the scope of to leave the present invention.

An embodiment of the invention is in the drawing shown and is described in more detail in the following description explained. Show it

Figure 1 is a side view, highly schematic, of an embodiment of an inventive device for making holes in a wheel of a motor vehicle.

Fig. 2 on an enlarged scale, also partially schemati based, a side view of a holding device for a wheel, as used in the device of FIG. 1;

Fig. 3 in a greatly enlarged scale a sectional view of a section of the device according to FIGS. 2 and

Fig. 4 on an enlarged scale, also partially schemati siert and partially in section, a side view of a counter bearing, as used in the device of FIG. 1.

In FIG. 1, 10 indicates a machine tool, namely a numerically controlled machining center, with which machining steps on workpieces can be carried out successively under program control. Machining centers of the type of interest here are essentially provided to carry out machining steps, in particular by drilling or milling.

Of the machine tool 10 , only one spindle stock 11 is partially indicated in FIG. 1, the axis 12 of which extends vertically. A tool 13 , for example a drill or a milling cutter, is held in the headstock 11 in a manner known per se.

On a workpiece table 14 of the machine tool 10 there is a clamping device 20 for workpieces. The Spannvor device 20 includes a mounting plate 21 which is fixedly connected to the workpiece table 14 , in particular screwed.

On the mounting plate 21 there is a dividing head 22nd In the left half of FIG. 1, the dividing device 22 comprises a rotary drive 23 , which is defined by a horizontal axis 24 . The rotating device 23 carries on its right side in FIG. 1 a first clamping device 25 , for example a clamping plate. The rotating device 23 further comprises a motor 26 , which is only indicated schematically in FIG. 1, for example a stepper motor. The motor 26 is operated by a suitable control (not shown) in such a way that the first clamping device 25 can be rotated about the axis 24 in defined angular steps or to defined rotational positions, as indicated by an arrow 27 .

In the right half of FIG. 1, a counter bearing 30 of the dividing device 22 can be seen. Such a counter bearing 30 is used when the workpiece clamped in the parting device 22 is exposed to strong mechanical loads, so that a floating bearing is eliminated. The counter bearing 30 comprises a second clamping device 31 , likewise preferably a clamping plate, which is opposite the first clamping device 25 . The thrust bearing 30 is designed so that the second clamping device 31 is rotatable about the same axis 24 as the first clamping device 25 . With 32 and 33 two fluid connections on the counter bearing 30 are also designated, the function of which will be explained below with reference to FIG. 4.

A holding device 40 is clamped between the opposing clamping devices 25 and 31 . The Haltvor device 40 carries a wheel 41 for a motor vehicle. An arrow 42 indicates that the wheel 41 can thus also be rotated or pivoted about the axis 24 by means of the dividing device 22 . The wheel 41 is fixed in the holding device 40 in such a way that the axis of rotation or swivel axis 24 runs perpendicular to the wheel axis indicated by 43 .

Fig. 2 shows the situation in the area of the holding device 40 in further detail. The wheel 41 fixed on the holding device 40 is shown in broken lines in FIG. 2. The wheel 41 conventionally comprises a peripheral rim 45 and an essentially radially extending bowl 46 which is arranged in the region of one side, namely the upper side of the wheel 41 in FIG. 2.

In the bowl 46 , a plurality of fastening bores 47 distributed over a circumference are provided, which are used for later fastening of the wheel 41 to the corresponding receptacle of the motor vehicle. The axes of the fastening bores 47 run parallel to the wheel axis 43 .

Furthermore, the wheel 41 is provided in the region of the rim 45 with a valve bore 48 . The valve bore 48 extends with its axis inclined to the wheel axis 43 . For this reason, it is also necessary to pivotally mount the wheel 41 in the sub-assembly 22 (cf. FIG. 1), so that the tool 13 aligned in the vertical axis in one pivoting position of the sub-apparatus 22 has the mounting holes 47 and in the other pivoting position the mounting bores 47 can attach inclined valve bore 48 . In Fig. 2, Z and X are two of the three directions of movement of the tool 13 which can be measured by moving the headstock 11 .

The machine tool 10 with the clamping device 20 is so far of conventional design, as z. B. is described in DE-PS 37 35 858, to the disclosure of which reference is made to further individual units.

On the holding device 40 , a support 49 is arranged, which is ring-shaped or can be arranged individually at several circumferential positions of the wheel 41 . In the case of individual pads 49 , these can be offset, for example, by 120 ° in the circumferential direction.

The pad 49 is shaped so that it receives a rim flange 50 of the wheel 41 . By forming a step in the support 49 , the rim flange 50 can be centered and axially supported in this way. In order to fix the wheel 41 on the support 49 , hold-down devices 51 are provided. For example, three hold-down devices 51 can be arranged so as to be offset by 120 ° over the circumference of the wheel 41 . The hold-down devices 51 are each pivotable about a horizontal axis 52 , as indicated by an arrow 53 in FIG. 2. When the hold-down device 51 rests on the rim flange 50 , it clamps the wheel 41 with its underside 54 on an upper side 55 of the support 49 of the holding device 40 . The wheel 41 is then axially and radially fixed and could be machined by means of the tool 13 .

In view of the relatively large dimensions of the wheel 41 and thus the relatively large distance and lever arm from the bores 47 , 48 to the fixing points of the hold-down devices 51 on the rim flange 50 , undesirable deformations and vibrations can occur when the bores 47 and 48 are introduced.

According to the invention, it is therefore provided to support the bowl 46 from below. This is done in that a surface 58 on the underside of the bowl 46 is supported on an end face 59 of a support element 60 .

The support element 60 consists essentially of a piston-cylinder unit 61 , the piston of which consists of a first piston part 62 and a second piston part 63 . The piston 62 , 63 runs in a cylinder 64 , which in turn is surrounded by a ring 65 . When the piston 62 , 63 is actuated, it can be moved from bottom to top in FIG. 2 (and later the other way round again), as indicated by an arrow 66 . If the piston 62 , 63 is moved upwards after the tensioning of the wheel 41 by means of the hold-down device 51 , its end face 59 finally comes into contact with the surface 58 of the bowl 46 and supports it. The bores 47 , 48 can then be introduced without any problems because the processing point (bores 47 , 48 ) is in the immediate vicinity and above the supporting end face 49 of the support element 60 .

FIG. 3 shows the lower left edge of the support element 60 in FIG. 2 in a sectional view, the sectional plane being in the plane of the drawing in FIG. 2.

It can be seen in Fig. 3 right above that the two piston parts 62, 63 telescopically run into each other. Their axial positioning relative to one another can be adjusted in predetermined steps by mechanical catches. For this purpose, several threaded bores 68 , 68 a are distributed in the first piston part 62 in the axial direction. . . arranged. By means of a screw 69 which penetrates the second piston part 63 radially, the first piston part 62 can be screwed into one of the threaded holes 68 , 68 a by screwing the screw 69 . . . can be fixed in the axial direction relative to the second piston part 63 . It is understood that, in order to avoid tilting, several rows of threaded holes 68 , 68 a or screws 69 can be arranged distributed over the circumference of the support element 60 , as shown in FIG. 2.

The cylinder 64 is provided in its upper half in FIG. 3 on the inside with a circumferential annular groove 70 . The annular groove 70 is of finite axial extent. An annular shoulder 71 runs in the annular groove 70 and is provided on the outer circumference of the second piston part 63 , approximately halfway up in the illustration in FIG. 3. The annular shoulder 71 thus forms a piston, on the two sides of which 70 cylinder spaces 72 and 73 are present in the annular groove. By means of fluid lines 74 , the cylinder spaces 72 , 73 can be optionally controlled, so that the piston formed by the annular shoulder 71 runs in the axial direction in the cylinder formed by the annular groove 70 . Of course, a spring can also be arranged in one of the cylinder spaces 72 , 73 , so that only one of the two cylinder spaces 72 or 73 has to be acted upon by a fluid and the resetting can take place by spring force.

Since the annular shoulder 71 is arranged on the outer circumference of the second piston part 63 and the second piston part 63 has a considerable diameter, the effective area of the piston formed by the annular shoulder 71 in connection with the radial depth of the annular groove 70 and the annular shoulder 71 is so large that the required axial force of the piston 62 , 63 can be generated by compressed air, which is taken from a conventional operating compressed air system (for example 8 bar).

In the lower part of FIG. 3 it can also be seen that the second piston part 63 can be mechanically locked in the cylinder 64 .

For this purpose, a radial bore 78 is made in the cylinder 64 , preferably at a plurality of evenly distributed circumferential positions, which passes inwards and to which another radial bore 79 of larger diameter adjoins from the outside. A fixing element 80 runs in the radial bores 78 , 79 . The fixing element 80 consists essentially of a piston 81 which runs in the radial bore 79 of larger diameter and of a piston rod 82 which runs in the radial bore 78 of smaller diameter.

As can be clearly seen from FIG. 3, the piston rod 82 rests on the right with its end surface 83 on the surface 84 forming the outer circumference of the second piston part 63 . Suitable material pairing ensures that there is enough friction in this system.

Since the piston 81 is dimensioned radially smaller than the radial bore 79 of larger diameter, cylinder spaces 85 and 86 are formed on both sides of the piston 81 , the left cylinder space 86 in FIG. 3 being delimited on the left by the ring 65 . The cylinder spaces 85 , 86 can be controlled by means of lines 87 . The dimensioning is again chosen so that control by means of compressed air from an operational compressed air network is possible. Also in this case, of course, single-acting or double-acting piston-cylinder arrangements are possible.

When the fixing element 80 is actuated, compressed air is conducted into the left cylinder space 86 . The piston rod 82 then abuts the second piston part 63 with its end surface 83 and fixes it in the axial direction. This axial locking is particularly expedient if a compressible fluid (compressed air) is used to actuate the pistons 62 , 63 . Because of the axial locking, the support function of the support element 60 can then be ensured when the piston 62 , 63 is extended.

Fig. 4 shows the counter bearing 30 of the sub-apparatus 22 in more detail.

First of all, it can be seen from FIG. 4 that the already mentioned second fluid connection 33 serves for supplying the lines 74 , 87 via corresponding channels. This means that the two piston-cylinder arrangements previously described in detail with reference to FIG. 3 for the axial movement of the piston 62 , 63 or the confirmation of the fixing element 80 can be supplied with fluid, in particular compressed air, via the counter bearing 30 . External piping or tubing is therefore not necessary.

The thrust bearing 30 serves only to support the Haltvor device 40 in the vertical direction when the tool 13 loads the workpiece in the Z direction when the headstock 11 comes down. If this load is too great, a flying arrangement of the workpiece holder switches off, as already mentioned.

When drilling holes that lie outside the longitudinal center plane of the wheel 41 , however, an additional disturbance can occur. In Fig. 1 this is denoted by d, the distance z. B. has a valve bore 48 from the longitudinal median plane of the wheel 41 . If the headstock 11 moves downward in the illustration in FIG. 1 and the tool 13 exerts an axial force on the wheel 41 at the location of the valve bore 48 , a torque also arises about the pivot axis 24 because the vertical machining force with the distance d from the Swivel axis 24 engages the wheel 41 . With regard to the rotating device 23 , there are generally no problems because the motor 26 in the rotating device 23 is usually designed to be self-locking since the dividing device 22 is intended to keep the workpiece held by it stable in the pivot position it approaches. However, this does not apply to the conventionally unlocked counter bearing 30 . At a high load of the wheel 41 can, therefore, lead to a torsion of the retaining device 40 when it is held on the left side in a rotationally rigid in the rotating device 23, but can rotate on the right side slightly in the counter-bearing 30th

For this reason, it is provided according to the invention that the counter bearing 30 can also be locked in the direction of rotation.

From Fig. 4 it can also be seen that the counter bearing 30 comprises a housing 90 . The housing 90 is penetrated by a first cylindrical bore 91 which extends coaxially to the axis 24 . A shaft 92 runs in the bore 91 . The second tensioning device 31 is attached to the left end of the shaft 92 . The first cylindrical bore 91 supports the shaft 92 only on the axial sides of the housing 90 . In between, the first cylindrical bore 91 merges into a second cylindrical bore 93 with a somewhat larger diameter. In the second cylindrical bore 93 a bellows-like locking element 94 a, 94 b sit on both sides in the housing 90 . The locking elements 94 a, 94 b are meandering in the cross section shown in FIG. 4. They are also deformable in themselves. When the locking elements 94 are axially loaded, they thus expand in the radial direction. Since the locking elements 94 a, 94 b in the second cylindrical bore 93 are kept tight in the radial direction and they can each be supported on the outside on radial support surfaces 95 , the locking elements 94 a, 94 b can each be actuated in that they are from the inside forth in the axial direction. The locking elements 94 a, 94 b then expand radially inwards and lay under frictional symmetry to a longitudinal center plane 96 of the counter bearing 30 on a peripheral surface 97 of the shaft 92 . The shaft 92 is thus fixed or locked in the direction of rotation by friction.

Pistons 99 a, 99 b are provided for actuating the locking elements 94 , 94 b. The pistons 99 a, 99 b are also arranged symmetrically to the longitudinal center plane 96 . They include a first section 100 of smaller diameter close to the axis and a second section 101 of larger diameter remote from the axis. The first sections 100 lie against the locking elements 94 a, 94 b and actuate them. In contrast, the second sections 101 serve as piston surfaces. For this purpose, the second sections 101 run with their circumference in cylinder sleeves 102 a, 102 b, which are axially spaced and leave an annular space 103 between them in the longitudinal center plane 96 . The second sections 101 are also thinner in the axial direction than the first sections 100 , so that a central cylinder space 104 remains between the second sections 101 of the two pistons 99 a, 99 b. The cylinder space 104 communicates with the annular space 103 . The annular space 103 is in turn connected to the first fluid connection 32 via a radial bore 105 .

As can be clearly seen from Fig. 4, the second portions 101 of the pistons 99 a, 99 b are dimensioned very large in the radial direction. This means that with relatively low operating pressure over the very large effective area 106 of the pistons 99 a, 99 b, considerable axial forces can be exerted on the locking elements 94 a, 94 b. It is therefore also possible here to connect to the first fluid connection 32 a customary compressed air system with, for example, 8 bar operating pressure and nevertheless to apply the required high actuation forces for the locking elements 94 a, 94 b. For this purpose, the fluid flows from the first fluid connection 32 via the radial bore 105 and the annular space 103 into the cylinder space 104 and acts against the opposing active surfaces 106 on the pistons 99 a and 99 b, which then move in opposite directions to the outside. The first sections 100 of the pistons 99 a, 99 b then press axially on the locking elements 94 a, 94 b, so that these, as described above, lock the shaft 92 in the direction of rotation.

To release the lock only the pressure needs to be removed because the locking elements 94 a, 94 b are elastic and thus themselves ensure the necessary resetting of the pistons 99 a, 99 b.

Claims (9)

1. Device for making holes ( 47 , 48 ) in a bowl ( 46 ) or a rim ( 45 ) of a motor vehicle wheel ( 41 ) by means of a numerically controlled machining center ( 10 ), in which the wheel ( 41 ) in a clamping device ( 20 ) which is pivotable about an axis ( 24 ) perpendicular to the wheel axis ( 43 ) and which comprises a pivot bearing on both sides of the wheel ( 41 ), characterized in that the clamping device ( 20 ) is designed as a partial apparatus ( 22 ), one of the pivot bearings being provided with a positionable rotary drive ( 23 ) and the other pivot bearing being lockable in the pivoting direction as a counter bearing ( 30 ). 2. Apparatus according to claim 1, characterized in that the counter bearing ( 30 ) can be locked by means of friction. 3. Device according to claim 2 with from the clamping device ( 20 ) and engaging in the pivot bearing shafts ( 92 ), characterized in that the shaft ( 92 ) of the counter-bearing ( 30 ) via a clamping device ( 31 ) rotatably in a housing ( 90 ) of the counter bearing ( 30 ) is held, and that friction elements in the radial direction on a circumferential surface ( 97 ) of the shaft ( 92 ) can be applied. 4. The device according to claim 3, characterized in that the friction elements can be actuated by means of a piston ( 99 a, 99 b). 5. The device according to claim 4, characterized in that the piston ( 99 a, 99 b) via an active surface ( 106 ) with compressed air of an operating compressed air system can be actuated. 6. Apparatus according to claim 4 or 5, characterized in that two friction elements can be actuated simultaneously by means of two pistons ( 99 a, 99 b). 7. The device according to claim 6, characterized in that the pistons ( 99 a, 99 b) can be deflected in opposite directions and are acted upon by a common cylinder space ( 104 ) arranged between the pistons ( 99 a, 99 b). 8. The device according to one or more of claims 4 to 7, characterized in that each piston ( 99 a, 99 b) is guided on the shaft ( 92 ). 9. The device according to claim 8, characterized in that each friction element is designed as a bellows-like locking element ( 94 a, 94 b) which sits on the shaft ( 92 ) and radially thickens under axial load and, tightly in a cylindrical bore ( 93 ) held, supported on the one hand on a radial support surface ( 95 ) fixed to the housing and, on the other hand, in contact with the piston ( 99 a, 99 b).