DE202011003583U1 - Machine tool, in particular for wheel machining - Google Patents

Abstract

Machine tool for the machining of workpieces (26), with a support surface (43) for clamping the workpiece (26), a work spindle (22) movable at least along one axis (21) for holding a tool (23) for machining the workpiece (26), and a holding device (45) for the workpiece (26), the holding device (45) having at least three holding elements (44) for holding the workpiece (26), each on a linear, radially on a central axis ( 31) aligned movement path (55) can be fed to the workpiece (26), characterized in that the holding elements (44) are fed mechanically forcibly coupled via a common gear (46, 47, 52, 53).

Description

The present invention relates to a machine tool for machining workpieces, having a bearing surface for clamping the workpiece, a work spindle movable at least along one axis for holding a tool for machining the workpiece, and a holding device for the workpiece, wherein the holding device at least three Holding elements for holding the workpiece has, which can be delivered in each case on a linear, radially aligned on a central axis of movement path to the workpiece.

Such a machine tool is from the DE 10 2008 835 A1 known.

The known machine tool is used for the machining of workpieces, preferably of rotationally symmetrical workpieces such as motor vehicle rims, which are referred to below as rims. The known machine tool is used in particular for introducing bores for the later valve feedthrough and the wheel bolts.

To hold a rim during machining, the rim is in other known machine tools so on a support surface, for. B. the workpiece table or a weighing plate a Wiegenvvorrichtung placed that the hub hole for centering the rim is fitted onto a centering pin provided on the support surface, and that the lower rim flange rests on the support surface. Furthermore, several, for example three, piston-cylinder units for holding the rim are provided on the support surface. These piston-cylinder units are arranged distributed around the rim and each carry as a holding element a hold-down.

To hold the rim in this machine tool, the positions of the piston-cylinder units must first be adapted to the diameter of the rim to be machined, for which purpose the piston-cylinder units must be moved along a travel rail on the support surface and then anchored. Thereafter, the hold-down is pivoted by means of a swivel arm to the rim and then folded down from above onto the lower rim flange, whereby the rim is pressed from above against the support surface.

Apart from the fact that in the known machine tool, the piston-cylinder units with the swiveling and folding down holdings have a relatively complex mechanism, there is the further disadvantage that the piston-cylinder units take up much space in the working space, so that only rims up to a maximum diameter can be edited. Furthermore, as the diameter of the rims to be machined changes, the positions of the piston-cylinder units must be readjusted, and several movements with different axes are required to hold the rim. For centering beyond a centering mandrel is absolutely necessary.

To fix these problems, suggests the aforementioned DE 10 2008 835 A1 to move the holding elements parallel to the support surface in the direction of a central, perpendicular to the support surface extending workpiece axis. The workpiece is then centered over the central centering mandrel and held at its lower edge, wherein by suitably designed holding elements against the workpiece pressure exerted both in the direction of the centering mandrel extending through the central workpiece axis and in the direction of the support surface and thereby the workpiece both centered and held. On the centering mandrel may therefore be waived if necessary.

For rims is suitable for centering and holding in particular the lower rim flange, which rests directly on the support surface when placing the rim, which is why the known holding elements lie only a short distance above the support surface. It is sufficient if the holding elements are each movable in a single direction, namely in the direction of the workpiece, in a plane parallel to the support surface.

The holding elements are moved independently in the known machine tool via their own adjusting devices. However, it is mentioned that the holding elements can also be moved synchronously with one another in the case of rotationally symmetrically configured workpieces, ie they can simultaneously press from opposite directions against the workpiece from outside and thus additionally contribute to the centering. This can be done mechanically or electronically by a synchronized drive of all holding elements.

In particular rims can be clamped exactly centered by this synchronization of the holding elements. An adjustment effort for the exact positioning of the rim does not apply. An adaptation to different workpiece diameter can be realized quickly and in a very simple manner.

Although the known machine tool has proven itself in the processing of wheels, the holding device described specifically for the workpieces is structurally complex and sees the proposed synchronous movement of the holding elements just not before.

The present invention is therefore an object of the invention to provide a machine tool of the type mentioned, in which the holding device is structurally simple and allows a synchronous method of holding elements, without giving up the advantages of the known machine tool.

This object is achieved on the basis of the aforementioned machine tool according to the invention that the holding elements are mechanically positively coupled via a common transmission.

In this way, the object underlying the invention is completely solved.

Due to the common mechanical transmission, the holding device is composed of a few elements and builds very small. The mechanical positive coupling also makes it possible to dispense with the centering mandrel, without the reliability and centering is affected during the clamping of the workpiece.

The gear can also be constructed self-locking, so that the required holding power can be reliably provided.

It is preferred if the transmission has a screw drive for each holding element, which is actuated via a common drive element.

The drive element preferably comprises a ring gear, which is driven by an electric motor.

These measures are structurally advantageous because the transmission is so very small and inexpensive to manufacture.

It is preferred if each retaining elements is preferably arranged interchangeably on a tension shoe, which is moved by the transmission, wherein more preferably on the tension shoe, the support surface is formed.

If the tension shoe at the same time provides the support surface, results in a simple design, safe and reliable working holding device.

Due to the interchangeability of the holding elements, the transmission can be converted depending on requirements for different workpieces, so that a universal holding device is available. The new machine tool can thus be quickly and inexpensively converted to the processing of different workpieces.

It is particularly preferred in this case if the machine tool is designed for wheel rim machining, in particular for the introduction of bores and / or recesses in rims, and if the retaining elements are designed to engage over the lower rim flange of a rim to be machined.

Overall, it is preferred if four holding elements are provided, wherein the movement paths of each two adjacent holding elements to each other at an angle, and two opposing angles have an amount less than 90 °, preferably in the range between 60 ° and 40 °.

If four retaining elements are provided, the workpiece can be kept symmetrical. If the two smaller angles are then in the range of 60 ° to 40 °, the workpiece is on the one hand kept securely centered, on the other hand, the transverse dimensions are sufficiently low. This narrow construction arrangement is made possible by the inventively provided mechanical transmission.

The holding elements are adapted to the configuration of the workpiece to be machined.

It is provided that the holding elements are configured to engage in a groove or overlapping a flange on the workpiece, wherein the holding elements are configured and arranged such that on the workpiece in the clamped state by the holding elements a contact pressure on the workpiece in the direction of the Support surface is exercised.

As a result, a holding and centering of the workpiece is achieved in a particularly simple manner. Of course, as mentioned above, the retaining elements are adapted to the groove or flange disposed on the workpiece. To be able to work with the same machine tool different workpieces, for example, different rims, is also preferably provided that the holding elements are interchangeable, so that depending on the workpiece and the appropriate holding elements can be used.

Finally, it is provided that the holding elements have a clamping surface inclined with respect to the support surface, which is pressed for holding and centering a workpiece to be machined against a flange on the workpiece, whereby a pressure in the direction can be exerted on the support surface as well as in the direction of the central axis.

This not only allows a firm fit of the workpiece on the support surface, but also prevents tilting and at the same time contributes positively to the exact centering of the workpiece.

Further advantages will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

An embodiment of the invention is illustrated in the drawing and will be explained in more detail in the following description. Show it:

1 a schematic side view of a schematic diagram of a machine tool according to the invention for wheel rim machining;

2 a front view of the machine tool 1 ;

3 a plan view of a holding device for workpieces, in the machine tool 1 is used; and

4 in schematic side view of a holding element from the holding device 3 ,

In 1 is with 10 a machine tool, which is shown in a schematic, not to scale and detail faithful side view.

The machine tool 10 points to her machine frame 12 a first sledge 13 on, moving in the direction of a first axis 14 on guide rails 15 is movable. On the first sledge 13 is a second sled 16 over guide rails 17 in the direction of a second axis 18 movably arranged.

At the second sled 16 is a spindle head 19 in the direction of a third axis 21 movably mounted. In the spindle head 19 is rotatable a work spindle 22 stored, which at its lower end a tool 23 wearing.

On the machine frame 12 is also a workpiece table 24 provided on a weighing device 25 is arranged, which is a schematically indicated workpiece in the form of a rim 26 carries in a manner to be described on a cradle plate 27 is stretched.

The weighing plate 27 is one parallel to the first axis 14 extending pivot axis 28 in the direction of the arrow 29 pivotable. Furthermore, the rim 26 by a fourth, parallel to the third axis 21 running workpiece axis 31 rotatable.

By moving the spindle head 19 and thus the work spindle 22 in the three axes 14 . 18 . 21 , which are commonly referred to as x, y and z axis, as well as by pivoting the weighing plate 27 around the pivot axis 28 and / or rotating the rim 26 around the workpiece axis 31 , can the rim 26 with the tool 23 be edited in different places.

Further general details and the basic mode of operation of such a machine tool are generally known to the person skilled in the art and should therefore not be further elaborated here.

2 shows a more detailed front view of a machine tool according to the invention 10 , where the in 1 shown means for moving the tool 23 So in particular the sled 13 . 16 and guide rails 15 . 17 , not shown here and only the tool 23 even with the work spindle 22 and the spindle head 19 are shown.

The on the workpiece table 24 arranged weighing device 25 comprises two spaced cheeks in a conventional manner 32 . 33 , between those around the pivot axis 28 swiveling the U-shaped weighing plate 27 is stored, on which the workpiece, in this case the rim 26 is clamped for processing. On the cheek 32 is still a drive 34 to recognize, over which the U-shaped weighing plate 27 around the pivot axis 28 from the in 2 shown horizontal position by up to 180 °, possibly even by 360 °, can be pivoted.

In the rim 26 be by means of the tool 23 which is then a drilling tool, holes 35 for the later implementation of wheel bolts and a valve bore 36 brought in. This is the rim 26 around the pivot axis 27 so swung that the tool 23 through a recess 37 in the weighing plate 27 through, so to speak from the inside the desired holes 35 . 36 in the rim 26 can contribute.

For introducing the holes 35 for the screw bushing is the rim 26 swiveled by 180 °. To the diagonally in the rim 26 extending valve bore 36 in the rim 26 bring in the rim 26 in contrast, pivoted by less (or more) than 180 °, so that the introduction of this valve bore 36 the tool 23 only one Feed along the (in z-direction) third axis 121 must perform.

To the rim 26 centric on the U-shaped cradle plate 27 to harness is on the cradle plate 27 in the prior art one with a center hole 38 in the rim 26 cooperating centering mandrel 39 intended. The outer diameter of the conical centering mandrel 39 is at the inner diameter of the center hole 38 adapted as a centric bore in the rim 26 is formed and forms the hub hole.

The conical outer diameter of the centering mandrel 39 is designed so that the rim 26 im on the centering pin 39 plugged state exactly on the cradle plate 27 rests, leaving the rim 26 with the center hole 38 on the centering pin 39 and with its flange-like edge, so the rim flange 41 , on the cradle plate 27 supported.

It should be mentioned that the use of a centering pin 39 at the new machine tool 10 is not absolutely necessary, since the holding device to be described below sufficient centering of the rim 26 cause. In addition, with the omission of the centering pin 39 A whole series of advantages are connected.

First, the center hole 38 So, the hub hole, on the new machine tool 10 be reworked, since the center hole 38 not from a centering pin 39 is busy. On the other hand, at the thus freely accessible center hole 39 with a probe 42 be checked if the rim 26 centric on the cradle plate 27 is mounted. In addition the in 2 schematically indicated touch probe 42 instead of the tool 23 in the work spindle 22 clamped or moved over its own delivery device.

For soft rims 26 It also prevents being in the rim 26 Tensions occur because they are between the centering pin 39 and the at 43 indicated support surface for the rim flange 41 braced. This danger is especially true when the center hole 38 was not made to fit.

For holding and centering the rim 26 during processing are at least three, preferably four in the weighing plate 27 integrated holding elements 44 provided radially on the rim flange 41 are adjustable. The holding elements 44 are thereby moved linearly in a direction parallel to that through the axes 14 and 18 spanned xy plane and perpendicular to the central workpiece axis 31 runs in the z direction 21 extends.

The holding elements 44 are designed so that they the rim 26 hold in a centered position during machining. This succeeds by the holding elements 44 to the conditions of the workpiece, in this case the rim 26 , are adapted to engage in a corresponding groove on the workpiece or the rim flange 41 can spread over. The holding elements 44 are designed so that they both a pressure against the rim 26 in the xy plane on the central workpiece axis 31 to as well as in z-direction 21 on the support surface 43 exercise to both center the workpiece as well as hold securely.

It should be mentioned at this point that with the term "bearing surface" on which the workpiece is clamped for machining, depending on the configuration of the machine tool 10 a clamping surface both on the workpiece table 24 as well as on the cradle plate 27 to be understood. In certain embodiments, the in the 1 and 2 shown weighing device 25 intended. For other machine tools 10 in particular, when the workpiece does not have to be pivoted during machining or the pivot axis 28 - As with a swivel head - in the tool 23 is realized, the workpiece directly on the workpiece table 24 clamped.

The holding elements 44 are part of a 3 shown in a schematic plan view holding device 45 ,

The holding device 45 includes a circular sprocket 46 which is arranged concentrically to a vertical axis, the clamped rim with the workpiece axis 31 coincides. In mesh with the sprocket 46 is a bevel gear 47 that on a wave 48 sitting over a motor 49 is driven by an electric motor.

By appropriate control of the engine 49 can the sprocket 46 thus along a double arrow 51 be turned back and forth.

The holding device 45 also includes four threaded spindles 52 , each with a bevel gear 53 connected to the sprocket 46 in meshing engagement. On every threaded spindle 52 is a holding element in the manner of a threaded spindle nut 44 arranged. The threaded spindles 52 are with their axis 54 radially to the central axis 31 too aligned. Along this axis 54 become the holders 44 proceed when the engine 49 is controlled. This feed movement of the holding elements 44 is by a double arrow 55 characterized.

The holding elements 44 are thus mechanically positively coupled and are moved synchronously. The sprocket 46 , the threaded spindles 52 and the bevel gears 47 . 53 thus form a gear via which the retaining elements 44 mechanically positively coupled be delivered.

The gearbox is formed by appropriate choice of gears - as it is known for other applications - self-locking, so that even with a de-energized motor 49 for a secure grip of the rim 26 is taken care of.

When the retaining elements 44 initially in the delivery direction 55 to each other at the same distance from the axis 31 aligned, they capture a rotationally symmetrical workpiece such as a rim 26 synchronously and simultaneously at four circumferential points and thus press in a centric position to the axis 31 , The individual radial axes 54 can each other an angle 60 each of 90 °.

But it is also possible to design two opposing angles smaller and accordingly the two other, opposite angles greater than 90 °. This has the advantage that the dimensions of the holding device 45 in the direction of the bisector 61 the two larger angles is less than transverse to it. This is constructively advantageous. When the two smaller angles are in the range of 60 ° to 40 °, the rim becomes 26 on the one hand kept safely centered, on the other hand, the transverse dimensions are sufficiently low.

This arrangement is made possible only by the common mechanical transmission with a single drive element.

Due to the design of the retaining elements 44 becomes the rim 26 on the support surface 43 pressed, as it is now based on the 4 is discussed.

In 4 is a holding element 44 shown in a schematic side view. The holding element 44 is interchangeable on a tension shoe 56 mounted in which a nut thread 57 for the threaded spindles 52 is provided. nut thread 57 and threaded spindle 57 So form a screw, which is driven by a drive element, which through the sprocket 46 is formed.

The tension shoe 56 points to its surface on which the holding element 44 is mounted, the bearing surface 43 on. On this support surface 43 comes the rim flange 41 to lie when a rim to be machined 26 to be clamped in the machine tool.

By moving the clamping shoes 56 in delivery direction 55 come clamping surfaces 58 and possibly 59 of the holding element 44 in contact with the rim flange 41 and press this on the support surface 41 and in the direction of the central axis 31 , The clamping surface 58 runs obliquely to the support surface 43 , so that they simultaneously clamping force in the direction of the axis 31 and on the support surface 43 to exercise.

Because the tension shoe 56 at the same time the bearing surface 43 provides, results in a simple design, safe and reliable working holding device 45 that just by adjusting the tensioning shoes 56 along the feed direction 55 not just the rim 26 centered and tensioned, but also on rims 26 different diameter can be adjusted.

The sprocket 46 may possibly together with the threaded spindles 52 and the engine 49 be sunk in the cradle plate. In 2 is a designated, circular encircling annular channel 62 shown.

Due to the interchangeability of the retaining elements 44 If required, the gearbox can be converted for different workpieces.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008835 A1 [0002, 0007]

Claims (11)

Machine tool for machining workpieces ( 26 ), with a bearing surface ( 43 ) for clamping the workpiece ( 26 ), one at least along one axis ( 21 ) movable work spindle ( 22 ) for holding a tool ( 23 ) for the machining of the workpiece ( 26 ), and a holding device ( 45 ) for the workpiece ( 26 ), wherein the holding device ( 45 ) at least three retaining elements ( 44 ) for holding the workpiece ( 26 ), each on a linear, radial to a central axis ( 31 ) oriented trajectory ( 55 ) on the workpiece ( 26 ), characterized in that the retaining elements ( 44 ) via a common transmission ( 46 . 47 . 52 . 53 ) are supplied mechanically positively coupled. Machine tool according to claim 1, characterized in that the transmission ( 46 . 47 . 52 . 53 ) is constructed self-locking. Machine tool according to claim 1 or 2, characterized in that the transmission ( 46 . 47 . 52 . 53 ) for each retaining element ( 44 ) a screw drive ( 52 . 57 ), which via a common drive element ( 46 ) is pressed. Machine tool according to claim 3, characterized in that the drive element ( 46 ) a sprocket ( 46 ), which is driven by an electric motor. Machine tool according to one of the preceding claims, characterized in that each retaining element ( 44 ) preferably interchangeable on a tension shoe ( 56 ) which is moved by the transmission. Machine tool according to claim 5, characterized in that on the tension shoe ( 56 ) the bearing surface ( 43 ) is trained. Machine tool according to one of the preceding claims, characterized in that four retaining elements ( 44 ), the trajectories ( 55 ) of two adjacent holding elements ( 44 ) to each other an angle ( 60 ), and two opposing angles ( 60 ) have an amount less than 90 °, preferably in the range between 60 ° and 40 °. Machine tool according to one of the preceding claims, characterized in that the holding elements ( 44 ) for engaging in a groove or overlapping a flange ( 41 ) on the workpiece ( 26 ) are configured, wherein the holding elements ( 44 ) are configured and arranged such that on the workpiece ( 26 ) in the clamped state by the holding elements ( 44 ) a contact pressure on the workpiece ( 26 ) in the direction of the support surface ( 43 ) is exercised. Machine tool according to one of the preceding claims, characterized in that the machine tool ( 10 ) for wheel rim machining, in particular for the introduction of bores ( 35 . 36 ) and / or recesses in rims ( 26 ), is configured. Machine tool according to claim 9, characterized in that the holding elements ( 44 ) for reaching over the lower rim flange ( 41 ) of a rim to be machined ( 26 ) are configured. Machine tool according to one of the preceding claims, characterized in that the holding elements ( 44 ) one with respect to the support surface ( 43 ) oblique clamping surfaces ( 58 ) for holding and centering the workpiece to be machined ( 26 ) against a flange ( 41 ) and thereby a pressure both in the direction of the workpiece support surface ( 34 ) as well as in the direction of the central axis ( 31 ) exercise.

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