The invention relates to an apparatus for establishing a concomitting movement of a working st tion operating on subjects circumconveyed on a rotary table driven by a motor rigidly mounted on the machine frame.

By many automated working processes subjects are carried on a rotary table from one working station to another. When a subject reaches a new station, the rotation of the table is stopped for the duration of the operation. The table is re- started to convey the subject to the next working station as well as to convey a new subject to the first mentioned working station.

Due to the fact that rotary tables usually are quite heavily built and often have a large diameter, they subsequently also have a large momentum. When positioning the subjects to be operated on lined up with the working stations, the braking and accelerating of such bodies of large momentums call for increased forces and induce the risk of harmful vibrations. By large rotary tables it is, therefore, preferred to let the table rotate at constant speed while the working stati¬ on rotates intermittently locked to the table allowing the wor¬ king operations to be safely carried out. A quick counter rotation of the working station will bring it back to meet the next subject to be operated on while once again being locked to the rotary table. This reciprocating movement along an arc concentric with the table rotation synchronizing the movements of the working station and the rotary table may be provided by appropriate cams and levers. Selecting one combination of cams and levers defines a fixed pattern of movements for the working station. Altering this pattern is only possible by changing the cam and lever combination, which again only is possible during a time consuming complete machine stop.

The object of the invention is to provide a concomit- ting mechanism allowing a more flexible control of the

synchronizing movement and hence avoiding any mechanical changes needed to alter the movement pattern.

This is obtained by an apparatus of the kind described in the opening paragraph, which apparatus according to the invention is characterized by the fact that the movement of the working station is provided by a controllable motor mounted rigidly on this working station and having its output shaft coupled to the rotary table by means of a slackless transmission. This construction makes it possible to control the concommitting movement of the working station regarding speed and direction solely by controlling the motor of the working station. Thereby, the parameters of the movement patterns may easily be altered between the movements as well as during the movements.

The motor of the working station may through its transmission be coupled to the same driving wheel on the rotary table as is the table drive motor through its respective transmission. The slackless transmission may be provided by meshing gear wheels or by toothed belts engaged by corresponding sprocket wheels.

When a toothed belt transmission is chosen, it is even possible to establish the transmission to the rotary table from the rotary drive motor as well as from the motor of the working station through a common toothed belt.

According to an embodiment of the invention, the motor of the working station may through its output schaft be coupled rigidly concentric to the rotary table as is the rotable table drive motor.

In the following the invention will be described with reference to the drawings, wherein

Figure 1 schematically shows an apparatus according to the invention equipped with gear wheel transmission , and

Figure 2 shows a detail of another embodiment of the apparatus shown in Figure 1,

Figure 3 schematically shows an apparatus according to the invention equipped with toothed belt transmission.

Figure 4 shows a detail of another embodiment of the appararus shown i figure 3,

Figure 5 schematically shows an apparatus according to the invention having the table drive motor as well as the working station drive motor coupled with their output schafts concentric to the rotary table, and

Figure 6 shows the coupling according to Figure 5 with the components pulled apart.

In Fig. 1, a rotary table 5 is turning at constant speed around a shaft 11, which through a st- tension 9 is secu¬ red to the machine frame 16. The rotary table 5 is driven by a motor 8 mounted rigidly on the machine frame 16. The output shaft of this conveyor motor 8 is meshing through a gear 7 with a gear 6 mounted rigidly on the rotary table 5.

A working station is symbolized by a platform 1, whereupon may be placed any kind of apparatus for carrying out an operation on a subject conveyed by the rotary table 5. The concommitting part 3 carrying the platform 1 is pivoting around the shaft 11 supported by a thimble 10. Hence, it is ensured that the arc described by the platform 1 is concentric with the rotation of the rotary table 5.

The pivoting movement of the platform 1 relative to the rotary table 5 is provided by a motor 4 mounted rigidly on the concommitting part 3. The output shaft of this pivot motor 4 is meshing through a gear 2 with the gear 6.

Supposing the conveyor motor 8 is running anticlockwise at constant speed as indicated by the arrow 13, the rotary table 5 will likewise turn at constant speed but clockwise as indicated by the arrow 12. When the pivot motor 4

is passive and blocked, a rigid connection between the rotary table 5 and the concommitting part 3 is established, and hence the working station symbolized by the platform 1 is locked to and concommitting accurately with the rotary table 5. Rotating the gear 2 by activating the pivot motor 4 will rotate the platform 1 relative to the rotating table 5.

At a certain anticlockwise rotational speed of the pivot motor 4 it will be possible to keep the platform 1 sta¬ tionary to the machine frame 16. Higher anticlockwise speeds of the pivoting motor 4 will rotate the platform 1 in an anticlockwise direction relative to the machine frame 16.

By careful setting of the pivoting speed and timing of the energizing and de-energizing of the pivot motor 4 it is, therefore, possible to have the platform a) concommitting with the rotary table 5 but rotating relatively to the machine frame 16, or b) returning to its initial position relative to the machine frame 16 while reciprocating along the circumference of the rotary table 5.

If an apparatus for working on subjects conveyed by the rotary table 5 is mounted on the platform 1, it will in case a) be possible to have apparatus and subject lined up rigidly for a period of time necessary to carry out a work operation.

At the end of the work cycle the working station may in case b) leave the subject previously worked upon and pivot back to be lined up with a subject conveyed subsequent to the one which has just been worked upon. The concommitting movement of the platform 1 is solely controlled by controlling the energization of the pivot motor 4, and the movements may easily be varied by varying this energization, i.e. the parameters of the movement may even be changed between two consecutive movements.

It is obvious that the directions of the involved parts may be reversed simply by reversing the rotations of the motors.

In the shown embodiment. Fig. 1, the conveyor motor 8 and the pivot motor 4 are coupled to the same gear on the rotary table 5. Thereby the movement of the concommitting part 3 relative to the rotary table 5 is limited, as the gears 7 and 2 should never meet. Should it be necessary to stretch the movements beyond these limits, a separate gear 6 ¹ may, as shown in Fig 2, be mounted on the shaft 11 to receive the driving force from the motor 8.

In Fig. 3, the meshing gears have been exchanged with a toothed belt and wheel arrangement.

The pivot motor 4, the conveyor motor 8, and the rotary table 5 in this embodiment have been linked together by a toothed belt 17. The rotary table is driven by the conveyor pulley 7' at constant speed, while the pivot pulley 2' creates the concommitting/reciprocating movement. Two sets of belt tensioning wheels 18 and 19 enable the belt at all times to be in tight contact with the driven pulley 14 of the rotary table 5 and the driving pulleys 2' and 7' . The tensioning wheels 18 of the conveyor motor 8 are fixed to the stator of the conveyor motor, and the tensioning wheels 19 of the pivot motor 4 are fixed to the stator of the pivot motor. To obtain similar movements, as described in Fig. 1, the rotations of the conveyor motor 8 and the pivot motor 4 must be reversed in all phases of the operation.

In the shown embodiment, Fig. 3, the conveyor motor 8 and the pivot motor 4 are coupled to the rotary table 5 by means of a common toothed belt 17. Thereby the movement of the concommitting part 3 relative to the rotary table 5 is limited, as the tensioning wheels 18 and 19 should never meet. Should it be necessary to stretch the movements beyond these limits, the two motors 4 and 8 may, as shown in Fig. 4, via two separate toothed belts 17 and 17' and sprocket wheel assemblies, be coupled to the rotary table 5, which is provided with two parallel pulleys 14 and 14' .

As shown in Figure 5, the table drive motor and the and the pivot motor may both be coupled with their shafts concentric with the axis of the rotary table. This coupling may be obtained by the shafts having a key 20 engaging a corresponding recess 21 in a central bore in the rotary table, as illustated in Figure 6 where the motors 4 and 8 are axially pulled out of engagement with the rotary table 5.