WO2011089236A1

WO2011089236A1 - Two-axis rotary table assembly

Info

Publication number: WO2011089236A1
Application number: PCT/EP2011/050860
Authority: WO
Inventors: Hansruedi Lehmann; Heinz Lehmann; Peter Lehmann; Thomas Muralt
Original assignee: Peter Lehmann Ag
Priority date: 2010-01-25
Filing date: 2011-01-21
Publication date: 2011-07-28
Also published as: EP2347854A1

Abstract

A rotary table assembly (1, 72) having at least two axes is created by connecting two drives via a connecting element (30, 72). More specifically, the connecting element (30, 72] allows attaching the second drive (5), that is moved by the first drive (3) in the rotary table (1), in at least two positions or alternatively in a single position. Multiple positions allow a better adaptation of the rotary table assembly (1) to changing requirements. Due to the uncomplicated attachment of the connecting element, the rotary table assembly is easier to produce.

Description

Two-Axis Rotary Table Assembly

The present invention relates to a rotary table assembly having at least two axes according to the preamble of claim 1. Furthermore, the invention relates to a method for producing such a rotary table assembly.

Rotary tables are used to retrofit additional axes on machine tools such as e.g. machining centers, grinding machines, engraving machines, etc. A rotary table allows bringing the workpiece into a position in which the machined area is better accessible for the tool or accessible at all. To this end it is often necessary to rotate the workpiece in two axes. Such tables are known in the art. However, many variants are being produced to fit the particular use each time. Thus it has often been necessary to produce a

specially adapted two-axis rotary table for a particular production project. The need of providing many different variants that are produced in correspondingly small numbers, or the need of custom-built tables entails high costs. Also, it is often the case that the specially adapted two-axis rotary table can no longer be used when a production project is terminated. Thus, this relatively expensive piece of equipment becomes worthless.

In addition, the construction of such rotary tables is relatively demanding. The available space is quite limited, and during machining, rough ambient conditions result from loose workpiece cuttings and chips and splashing working fluids. Therefore, in motorized rotary tables that are required for fully automated machining, a high effort is necessary to protect the sensitive parts from external influences. Also known in the art are embodiments comprising a combination of a motorized rotary table and a manually adjustable rotary table. However, these have a limited range of applications; in particular, there is an increased probability that such a rotary table cannot be used any longer after a production change. A manual adjustment during automated machining of one and the same workpiece is generally excluded.

It is therefore an object of the present invention to provide a rotary table assembly having at least two axes that is better adaptable to changing requirements.

Another object is to provide a rotary table assembly having at least two axes whose production entails smaller costs.

A rotary table assembly that meets at least the first of the aforementioned objects is defined in claim 1. The further claims define preferred embodiments and production methods. Accordingly, it is essentially suggested to combine two single-axis rotary tables into a two-axis rotary table assembly, the connection between the two rotary tables being established by means of a connecting element, more

particularly a so-called adapter plate. The first rotary table on which the second rotary table is arranged and which thus generally swivels the latter about a swivel axis is hereinafter called the swivel drive. However, this drive need not necessarily be a rotary table proper. The second, swiveled rotary table is hereinafter called the rotary drive. Both drives are provided with a motor and usually with a gear unit that are known in the art. The adaptation of this assembly to different applications is achieved in a surprisingly simple manner by the fact that the adapter plate is provided with a plurality of fixtures for the rotary drive. Further advantageous possibilities or enhancements of the assembly are e.g. the following:

- The attachment of the adapter plate to the rotary drive essentially uses existing fastening means. - The adapter plate may be attached to the rotary drive by fastening means which simultaneously allow a radial and axial positioning of the adapter plate on the rotary drive relative to the swivel axis. - Design of the adapter plate as a replacement of a

removable housing portion of the rotary drive.

- The assembly may be additionally stabilized by a counter bearing that supports the free end of the rotary drive. The counter bearing is preferably designed in analogy to the bearing on the side of the swivel drive, in particular using an adapter plate.

Further advantages achieved by the invention will become apparent in the following description of a preferred

exemplary embodiment with reference to figures:

Fig. 1 Overall view of a two-axis rotary table assembly having a unilaterally supported rotary drive; Fig. 2 View of an adapter plate with fitting screw stubs ;

Fig. 3 Partial section through the adapter plate;

Fig. 4 Overall view of a rotary table assembly having a counter bearing;

Fig. 5 Overall view of a rotary table assembly as in Fig. 1 but with simplified adapter plate;

Fig. 6 View of a simplified adapter plate; and

Fig. 7 View of a rotary table assembly as in Fig. 5 but with counter bearing.

Fig. 1 shows an overall view of a rotary table assembly 1 for two axes. It comprises two drives, i.e. swivel drive 3 and rotary drive 5. Each of the latter includes a gear part 7, 9 with externally accessible outputs 11, 13. Flange mounted to the gear parts are motor parts 15, 17,

accommodating the motor and required electronics, in

particular. The housings of motor parts 15, 17 are composed of shaped parts 19, 21, preferably made of aluminum, that are closed by motor housing covers 23, 25. Gear part 7 is closed on its side facing away from motor part 15 by a gear cover 27. Motor housing covers 23, 25 as well as gear cover 27 are fastened by means of screws 29. In analogy to gear cover 27, such a cover can also be attached to gear part 9 of rotary drive 5. In the example, however, adapter plate 30 is mounted here. It follows that swivel drive 3 and rotary drive 5 (provided with gear cover instead of adapter plate 30) may generally be designed as normally applicable single- axis rotary tables. After disassembling the rotary table assembly, they may be further used as such or as components in a rotary table assembly of another kind. Adapter plate 30 is shown separately in Fig. 2. On its rear side, the means for its attachment to gear output 11 are visible. Firstly, the latter consist of a cylinder 33 with an O-ring 35 that is inserted into the hollow interior of gear output 11 in order to close it. Around cylinder 33, screws 37 (six of them in the example) are arranged whose threaded ends 39 are screwed into corresponding threaded holes in gear output 11 in order to fasten adapter plate 30 to gear output 11. Cylinder 33 particularly serves for radial positioning whereas screws 37 provide an axial fastening action to rotary drive 3.

For the attachment of rotary drive 5, two rows of fitting bores 41 are provided in adapter plate 30. From each side surface 43, respective threaded fixing bores 45 extend into each of fitting bores 41.

Fitting bores 41 are intended to receive the fitting head 47 of a fitting screw 49 (see Fig. 3) . Fitting screws 49 are screwed into the housing of gear part 9. Due to the

accurately fitting shape of their heads 47 in conjunction with the equally precisely shaped fitting bores 41, a radial positioning (crossed arrows 51) of adapter plate 30 relative to rotary drive 5 is already ensured when adapter plate 30 is placed on the front surface of gear part 9 with fitting screws 49 inserted therein. Particularly the fitting

elements (heads 47, fitting bores 41) are manufactured to narrow tolerances. For the axial positioning and for an impervious attachment of gear part 9 to adapter plate 30, head 47 is provided with a circumferential notch 53. In fixing bore 45, a fixing screw 55 (here a headless screw) is entered. The conical front end 57 of fixing screw 55 contacts the inclined front surface 57, 59 of notch 53. Due to the contacting inclined surfaces 59, a further tightening of fixing screw 55 produces an axial force applied to head 47 of fitting screw 49 in the direction of arrow 61. By driving-in of fixing screw 55 it is thus possible to pull gear part 9 toward adapter plate 30, i.e. to tighten it thereon and thus to achieve axial fastening and an impervious attachment to the adapter plate. As appears in Fig. 2, the four fitting screws 49 required can be fastened in adapter plate 30 in three different positions. Thus, the illustrated position causes gear output 13 to be located on the swivel axis of swivel drive 3 approximately. However, in this position, the size of a workpiece that can be fastened to gear output 13 is

laterally limited by swivel plate 30. In the uppermost position (using the uppermost fitting bores 63), gear output 13 is located outside the swivel axis and thus performs a circular motion as rotary drive 5 is swiveled. The latter has to be taken into account when guiding the tools of a machining center, but in return, the lateral limitation of the size of the attachable workpiece is essentially

eliminated . In the following, modifications of the described exemplary embodiment will be explained where identical reference numerals designate the same or analogous parts. In rotary table assembly 70, which otherwise corresponds to rotary table assembly 1, a simplified adapter plate 72 is used instead of an adapter plate 30 having different attachment possibilities of rotary drive 5. It distinguishes itself from adapter plate 30 in that only one set of fitting bores 41 (not visible) is provided and rotary drive 5 is thus attachable in the illustrated position only. The surprising simplicity of the construction is also

demonstrated by the fact that merely by exchanging the simplified adapter plate 72 for an adapter plate 30 it becomes possible to attach rotary drive 5 in different positions .

Fig. 6 shows adapter plate 72 separately in a view in analogy to Fig. 2.

Figs. 4 and 7 show variants of the rotary tables of Figs. 1 and Fig. 5, respectively, where the end of rotary drive 5 opposite the swivel drive is held in a counter bearing 75. Counter bearing 75 rests on a baseplate 77 that is connected to swivel drive 3. This construction results in a higher rigidity and thus resistance of the entire assembly to forces applied to gear output 13. On the side of rotary drive 5, counter bearing 75 has an output that corresponds to gear output 11. Thus, an adapter plate 30 or 72,

respectively, can simply be used between counter bearing 75 and motor housing part 17. In some cases it may be necessary to use a mirror-symmetrical embodiment. A particular

advantage in this arrangement is a rigid motor housing part 21 such as a shaped part. Moreover, the entire assembly as a whole is impervious, thereby eliminating the known problems in sealing motor part 17 from ambient influences in a machining center. In the same way as two independently utilizable single-axis rotary table drives can be obtained by dividing the rotary table and providing rotary drive 5 with a cover on the gear part and possibly also on motor part 17, it is possible to combine an existing rotary drive with another rotary drive into a two-axis rotary table in a simple manner on the spot. To this end, conversely, at least the cover of gear unit 13 has to be removed and replaced by an adapter plate 30 or 72. Due to the described fastening mode by means of fitting screws and laterally engaging fixing screws, simplest tools are sufficient therefor. The thus converted rotary drive 5 is then fastened to gear output 11 of a second single-axis rotary table or an equivalent drive that is thus turned into a swivel drive 3.

From the preceding description of exemplary embodiments, numerous modifications and complements are conceivable by the one skilled in the art without departing from the scope of protection of the present invention that is defined by the accompanying claims. In particular,

- Swivel drive 3 may have the same construction as rotary drive 5.

- Adapter plate 30 may have more or less fitting bores 41 in accordance with a greater or smaller number of possible radial positions of rotary drive 5. - A different pairing of point 57 of fixing screws 55 and the wall of notch 53 rather than inclined-inclined is used, e.g. a round point 57 on an inclined wall or a conical point 57 on the edge area of a steeper wall of notch 53.

Claims

1. Rotary table assembly (1) for moving a workpiece around at least two axes, comprising at least a first and a second motorized drive (3, 5) for a respective axis, characterized in that

- the second motorized drive (5) is attached to the first drive (3) via a coupling device so that the second drive is movable by the first drive,

- the coupling device comprises a connecting element (30) that is removably attached to at least one of the first and second drives, and

- the connecting element allows the attachment of the second drive in at least two positions.

2. Rotary table assembly (1) according to claim 1, characterized in that the two positions represent different distances of a workpiece that is attached to the rotary table assembly from the axis (62) of the first motorized drive (3) .

3. Rotary table assembly (1) according to any one of claims 1 to 2, characterized in that the connecting element (30, 72) is removably attached to the second motorized drive (5) by means of fastening elements (49) , at least one of the fastening elements, preferably the part of the fastening elements that is essential for the attachment of the

connecting element, being essentially bolt-shaped and the first end portion (47) of the fastening element being shaped to precisely match a complementarily shaped receptacle (41, 63) radially, the first fastening element end additionally comprising an axial clamping provision (53) , and the receptacle being located in the second motorized drive (5) or in the connecting element (30, 72) .

4. Rotary table assembly (1) according to claim 3, characterized in that the receptacle is essentially a hole (41, 63), the first fastening element end portion (47) is essentially a cylinder that is shaped to precisely match the receptacle radially and has a recess (53) as the axial clamping device (53), and the recess is at least partially provided with a wall portion (59) extending in a direction that significantly deviates from a right angle to the longitudinal axis of the fastening element (49) so that an axial traction can be produced by a fixing element (55) that enters into the recess radially.

5. Rotary table assembly (1) according to claim 4, characterized in that the receptacle (41, 63) is located in the connecting element (30, 72) and the connecting element has a fixture (45) for the fixing element (55), the fixture having an access for the fixing element to the receptacle.

6. Rotary table assembly (1) according to any one of claims 4 to 5, characterized in that the recess (53) is essentially a circumferential notch running around the first fastening element end portion (47) and the wall portion (59) is essentially a lateral wall of the notch, preferably the one situated near the end face of the first end portion of the fastening element (49) .

7. Rotary table assembly (1, 70) according to any one of claims 4 to 6, characterized in that the fixing element (55) is a screw and preferably a headless screw, and the fixture (45) is essentially a hole that is open toward the receptacle and provided with a thread for the fixing element .

8. Rotary table assembly (1, 70) according to any one of claims 1 to 7, characterized in that the second drive (5) is rotatable by the first drive (3) around a swivel axis (62) and a second connecting element (30, 72) is provided in the direction of the swivel axis on the second motorized drive (5) opposite the connecting element (30, 72), wherein the second connecting element is rotatably supported around the swivel axis in a bearing (75) .

9. Rotary table assembly (1) according to claim 8, characterized in that at least the means in the second connecting element for fastening the second motorized drive (5) are designed in the same way as those in the first connecting element.

10. Method for producing a rotary table assembly (1, 70) according to any one of claims 1 to 9, characterized in that a housing part of a rotary table drive (5) is removed and the connecting element (30, 72) is fastened to the drive using the fastening means for the housing part in order to obtain a second rotary table drive (5) , the rotary table drive being attachable to the connecting element in exactly one position or in at least two positions.