Rotary indexing table

A rotary indexing table having a plate which has drivers engaging into a driving groove of a barrel cam is provided. The plate is drivable via a barrel cam to make a rotary movement about an axis of rotation which is in turn drivable by a motor to make a first rotary movement about its longitudinal axis. An additional drive element connected drive-wise to the barrel cam is provided which is coupled to the plate via at least one coupling element.

The present invention relates to a rotary indexing table having a plate which has drivers engaging into a driving groove of a barrel cam, with the plate being drivable via the barrel cam to make a rotary movement about an axis of rotation which is in turn drivable by a motor to make a rotary movement about its longitudinal axis.

Such rotary indexing tables, as are generally known in various embodiments from the prior art, serve, for example, to transport a plurality of workpieces held on the said plate or on structures arranged thereon in each case by a rotation of the plate from one work station or mounting station further to a next work station or mounting station. This transport usually—but not necessarily—takes place within the framework of a cyclic operation in which the plate is rotated by an angular measure with every cycle, said angular measure being able to correspond, for example, to the angular distance between two adjacent workpieces arranged on the plate.

With heavy workpieces, a substantial strain on the components of the rotary indexing table occurs which also has to be taken account by a corresponding design of the drive. One of the limiting factors of the power transmission of the drive is the coupling between the driving groove of the barrel cam and the drivers engaging into said driving groove. To provide rotary indexing tables which are of particularly high performance, a second drive unit, i.e. a second barrel cam having a separate motor associated with one of these barrels, is therefore usually provided. Such a rotary indexing table is known, for example, from DE 10 2007 021 681 B3.

It is an object of the invention to provide a rotary indexing table which can also reliably cope with high strains. The rotary indexing table should be inexpensive to manufacture.

This object is satisfied in accordance with the invention by a rotary indexing table having an additional drive element which is connected drive-wise to the barrel cam and which is coupled to the plate via at least one coupling element.

In other words, the plate is driven by the barrel cam via the additional drive element and the coupling element in addition to the driving force provided via the known driving groove/driver coupling. A second barrel cam to increase the driving force supplied to the plate is thus not necessary. The additional mechanical coupling path relieves the driving groove and the drivers of the plate, whereby their limited driving force transmission no longer presets the maximum strain of the rotary indexing table as a limiting factor. Wear phenomena of the driving groove and of the drives are additionally minimized.

The surprisingly simple idea underlying the invention thus provides a simply structured and therefore reliable rotary indexing table which does not require any additional electrical, and therefore expensive, drive elements to improve the drive of the plate.

An advantageous further development of the rotary indexing table in accordance with the invention provides that the coupling element includes a shaft section which is rotatably arranged coaxial to the axis of rotation of the plate. This shaft section can, for example, be a substantially tubular hollow cylinder.

The coupling element is in particular rotationally fixedly connected to the plate and/or to the additional drive element. Expensive transmission elements are thereby omitted, for example. Such a coupling is moreover in particular of particularly high performance and less prone to damage. It must be mentioned in this connection that the rotationally fixed connection can be configured directly or indirectly. A connection is to be understood by an indirection connection which provides one or more interposed elements between the named components.

Provision can be made that the axis of rotation of the plate and the axis of rotation of the additional drive element are arranged coaxial.

In accordance with a further advantageous embodiment, the additional drive element includes an additional plate which has drivers engaging into the driving groove or into an additional driving groove of the barrel cam.

The plate and the additional drive element are in particular arranged substantially in mirror-symmetry with respect to a plane of symmetry which in particular includes the axis of rotation of the barrel cam. Such a type of construction is particularly compact. In addition, substantially the same components can be used for the plate and for the additional drive elements as well as for the respective drivers associated with them, which has a positive effect on the manufacturing costs of the rotary indexing table. Asymmetrical types of construction are in particular recommended in applications in which the additional drive element and the plate have different tasks; for example, when the additional drive element is only provided for the provision of a further mechanical coupling path and for the improvement of the support, whereas the plate can also be equipped with workpieces in addition to the aforesaid tasks. Specific construction space requirements can likewise make an asymmetrical type of construction necessary.

A uniform strain on the drive components of the rotary indexing table results when the plate and the additional drive element can be driven with substantially equal force by the barrel cam.

In the position of use of the rotary indexing table, the axis of rotation of the plate and/or the axis of rotation of the additional drive element can be arranged substantially vertical. The workpieces to be machined then “lie” on the plate. In contrast to this, an alternative type of construction has substantially horizontally arranged axes of rotation of the plate and/or of the additional drive element. This allows a particularly efficient use of the rotary indexing table since both the plate and the additional drive element are easily accessible from the side and thus workpieces arranged thereat can be machined particularly easily at oppositely disposed sides of the rotary indexing table. The additional drive element of the “vertical” variant of the rotary indexing table can, however, also generally be equipped with workpieces, e.g. from below.

The plate and/or the additional drive element can be coupled to a respective one flange each for the holding of a workpiece. This, for example, allows a simple adaptation of the rotary indexing table to the workpieces to be machined since only the flange has to be replaced when another type of workpiece should be machined.

Advantageous embodiments of the invention are described in the description, in the dependent claims and in the drawings.

FIG. 1shows a rotary indexing table10schematically in a plan view which has a rotatably supported plate12(indicated by a dashed line). The plate12is shown transparent inFIG. 1in order not to cover drivers14arranged at its lower side. The drivers14are distributed uniformly in the peripheral direction of the plate12and lie on an imaginary circle K whose center lies on an axis of rotation R of the rotatably supported plate12. The support of the plate12takes place by a housing20of the rotary indexing table10, as will be explained in the following in more detail with reference toFIG. 2. The drivers14have a longitudinal extent running perpendicular to the plane of the drawing ofFIG. 1and thereby engage into a driving groove16of a barrel cam18. The barrel cam18is rotatably supported about an axis of rotation R′ in the housing20which also serves for the support of the plate12.

To set the plate12into rotation, the barrel cam18is set into a rotary movement. The driving groove16running in spiral fashion around the barrel cam18takes along the drivers14on a rotation, whereby the plate12is in turn set into a rotary movement. This manner of drive of the plate12is generally known from the prior art. It is likewise known that the embodiment of the driving groove16together with the rotary driving movement of the plate12controls the rotary movement of the plate12. In other words, the driving groove16can have regions with different or varying gradients, deviating from the embodiment shown. Latching regions of the driving groove16can also be provided which extend perpendicular to the axis of rotation R′ in a plan view. With a suitable arrangement and number of drivers14, a cyclic operation of the plate12can then be generated, for example, without changing the drive speed of the barrel cam18. Such a drive can, however, also be realized with a constant gradient of the driving groove16by a correspondingly controlled drive of the barrel cam18.

The drive of the barrel cam18takes place by an electric motor22whose axis of rotation R″ is arranged parallel to the axis of rotation R′ of the barrel cam18. A driving torque generated by the motor22is transmitted in a manner known per se via a transmission24—in the present case a spur gear—to a drive shaft26of the barrel cam18, whereby the plate12is driven to make a rotary movement about the axis of rotation R in the manner described above. The axis of rotation R extends perpendicular to the axes of rotation R′, R″.

As initially explained, the coupling between the drivers14and the flanks of the driving groove16also represents a mechanically limiting factor for a reliable drive of the plate12with high strains. Specifically, this means that the left hand flank of the driving groove16running spirally around the barrel cam18is loaded when the plate12shown is driven to make a rotary movement in a counter clockwise manner. To reduce this strain and thus to improve the drive of the plate12, an additional mechanical coupling path is provided between the barrel cam18and the plate12, as is shown inFIG. 2.

FIG. 2shows a perpendicular section through the plate12, the barrel cam18and the housing20. It can be recognized that the plate12is rotatably supported in the housing20by an axial bearing28aand a radial bearing28r.

As already described above, the plate12is provided with drivers14. In the position of use of the plate12on which workpieces (not shown) to be machined—directly and/or indirectly—can be fastened, the drivers14are located at the lower side of the plate12. They engage into the driving groove16of the barrel cam18in the manner described above.

The plate12is, however, not only driven via the coupling of the drivers14with the barrel cam18. To provide a further mechanical coupling path between the barrel cam18and the plate12, the plate is additionally rotationally fixedly connected to a coupling cylinder32. The coupling cylinder32arranged coaxial to the plate12has a flange-like extension34at each of its end faces. The extension34at the upper end face in the position of use serves for the connection of the coupling cylinder to32to the plate12. The coupling cylinder32is in rotationally fixed connection with an additional plate36via the extension34at the other—lower—end face of said coupling cylinder.

The additional plate36is connected drive-wise to the barrel cam18in an analog manner as the plate12. The construction of the components associated with the additional plate36—e.g. drivers14′, bearings28a′,28r′—is identical to the corresponding components which are associated with the plate12. Only the spatial arrangement differs due to the fact that the additional plate36cooperates with the barrel cam18“from below”. The components are therefore arranged symmetrical to a plane of symmetry S which includes the axis of rotation R′ of the barrel cam18and which stands perpendicular on the common axis of rotation R of the plates12,36. No separate driving groove16is associated with the drivers14′ of the additional plate36, i.e. the drivers14,14′ engage into the same driving groove16. It is, however, by all means conceivable for specific applications that a separate driving groove is provided for the drivers14′ which can be a spiral groove offset in the axial direction parallel to the driving groove16, for example. This offset must also be taken into account in the arrangement of the drivers14′ in this case, said drivers coinciding with the drivers14in a direction parallel to the axis of rotation R.

It is ensured in a simple manner by the symmetrical structure of the “classical” coupling path and of the “additional” coupling path between the barrel cam18and the plate12—direct coupling between the barrel cam18and the plate12, on the one hand, and indirect coupling of these two components via the additional plate36and the coupling cylinder32, on the other hand—that the driving force is transmitted in substantially equal parts via the two coupling paths from the barrel cam18to the plate12. This also means that the maximum stress acting selectively on the loaded flank of the driving groove16is halved in comparison with the corresponding strains which occur in a rotary indexing table which only has the direct coupling between the barrel cam18and the plate12.

It is understood that the symmetrical embodiment of the plate12and of the additional plate36does not have to be provided in all cases. This embodiment is admittedly also advantageous with respect to the manufacturing costs since no additional components of a different constructional design are required for the provision of an additional mechanical coupling. However, the specific construction can be adapted to the respective present application profile. A coupling is, for example, conceivable via moving elements—for example gears—and/or via differently dimensioned components.

FIG. 3shows a perspective representation of the rotary indexing table10. The plate12, which is supported in the housing20, can be recognized at the right. Bores38can be recognized in the surface of the plate12which serve for the fastening of the drivers14, as can also be seen fromFIG. 2. The bores38can optionally also be provided for the direct or indirect fastening of workpieces. A plurality of different types of fastening can generally be used.

The housing30covers the barrel cam18which is substantially arranged completely in the interior of the housing20. As can be seen inFIG. 1, a shaft section of the drive shaft26of the barrel cam18projects out of the housing30. It is connected there to the transmission24which is surrounded by a transmission housing40inFIG. 3and is therefore not visible. The transmission24is in turn in connected to the motor22.

A further embodiment of the rotary indexing table10′ is shown inFIG. 4. In this respect, the housing20is arranged in a perpendicular position in the position of use so that the plate12and the additional plate36(both not visible) are likewise arranged in a respective perpendicular plane. The common axis of rotation R of the two plates12,36substantially extends in a horizontal axis. Due to the vertical arrangement of housing/plates, the plates12,36are easily accessible from both sides, i.e. both the plate12and the additional plate36can be provided with tools. In other words, twice the number of workpieces can be machined per unit of time using a rotary indexing table10′ in comparison with a conventional rotary indexing table.

In the rotary indexing table variant10′ shown inFIG. 4, a flange42is applied to each of the plates12,36. The flanges42serve for the fastening of workpieces and can be matched to the respective circumstances present.

FIG. 4also shows inter alia, in addition to the special features of the rotary indexing table10′ described above, an arrangement of the motor22which differs from that of the rotary indexing table10. With the rotary indexing table10′, the motor22and the housing20are not arranged on one side of the transmission24or of the transmission housing40, but are rather arranged on oppositely disposed sides. The axis of rotation R″ of the motor is, however, still arranged parallel to the axis of rotation R′ of the barrel cam18(not visible).

It is advantageous in this connection if the transmission24has a modular structure, i.e. if the transmission24can be brought into connection drive-wise with an input shaft or output shaft from both sides of the housing40. For this purpose, the housing40has two openings44on both end faces (see alsoFIG. 3), one each for the input shaft and for the output shaft. Such a modular structure reduces the manufacturing costs and expands the flexibility of use of the rotary indexing table in accordance with the invention since a conversion between the embodiments10,10′ can take place in a simple manner, for example. A replacement of the transmission24is namely not required for this purpose.

FIG. 5shows a perpendicular section through a further embodiment of the rotary indexing table10″. In this embodiment—contrary to the embodiment shown in FIG.2—the “classical” coupling path and the “additional” mechanical coupling path do not have a symmetrical structure. The plate12′ and the additional plate36′ of the rotary indexing table10″ are admittedly driven via drivers14and14′ respectively in the manner described above. However, the two embodiments differ from one another inter alia by the support of the plates12,36or12′,36′ respectively. The plate12′ of the rotary indexing table10′ is supported by two axial bearings28aand one radial bearing28r, whereas the additional plate36′ is only guided in its rotary movement by a radial bearing28r′. To simplify assembly, one of the axial bearings28ais associated with a ring element56which is connected to the housing20by bolts50.

The axial support of the elements rigidly connected to one another of plate12′, coupling cylinder32′ and additional plate36′ is substantially provided by the plate12′ due to the arrangement of the bearings28a,28r,28r′ described above. The additional plate36′ has a supporting effect on the support in the radial direction.

The additional plate36′ is made in much less solidly a manner than the plate12′ since it is not provided for an equipping with workpieces as standard. A cover plate48is fixedly connected to the housing20by bolts50and screens the additional plate36′ from the environment, for example to prevent the penetration of dirt.

The asymmetrical form of the rotary indexing table10″ is also reflected in the design of the coupling cylinder32′. The coupling cylinder32′ has—similar to the coupling cylinder32of the rotary indexing table10—extensions34′ which serve for the fastening of the plate12′ and of the additional plate36′ and whose shape is oriented to the contour of the barrel cam18to provide the greatest possible stability with simultaneous optimization of the construction space. An axial prolongation52′ of the coupling cylinder32′, however, passes through the additional plate36′ in the axial direction, while a corresponding axial prolongation52only partly penetrates into a central opening54of the plate12′.

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