Method of and apparatus for controlled closure of at least one clip around a filling material-free plait portion of a tubular casing at a filling material portion enclosed by the casing

1. A method of controlled closure of at least one clip around a filling material-free plait portion of a tubular casing at a filling material portion enclosed by the casing, wherein the at least one clip is closed with at least one closure device and wherein successive filling material portions are filled with a moved product flow with the filling material and in that operation the casing is withdrawn from a casing supply, the method comprising the steps of:

sensing the withdrawal movement of the casing between two successive closure operations over at least one of a short period of time and a short length portion; and

forming a control signal based on the sensed withdrawal movement therefrom; and

controlling the joint movement of the at least one closure device with the product flow of the filling material when filling the respective filling material portion based on the control signal by moving the closure device at least in a direction approximately parallel to the direction of movement of the product flow; and

closing the clip around the filling material-free plait portion during said joint movement.

2. The method of claim 1 further comprising: determining the withdrawal speed of the tubular casing during the sensing step.

3. The method of claim 1 where the step of forming the control signal for the joint movement of the at least one closure device comprises forming the control signal proportionally to the advance movement of the product flow of the filling material when filling the respective filling material portion.

4. The method of claim 1 where the step of controlling the joint movement comprises controlling the speed of the joint movement of the closure device relative to the advance speed of the product flow of the filling material when filling the respective portion.

5. The method of claim 1 further comprising filling the respective successive filling material portions with a continuously moved product flow of the filling material.

6. The method of claim 1 further comprising controlling the joint movement of a displacer device disposed at the end of the plait portion and with which the respective filling material-free plait portion is formed with the at least one closure device and the product flow of the filling material based on the sensed withdrawal movement of the tubular casing.

7. The method of claim 6 where the step of controlling the joint movement of the displacer device uses the same control signal as the closure device.

8. The method of claim 7 where the at least one closure device and the displacer device are jointly moved with the product flow upon filling of the respective filling material portion by means of respectively associated separate drives.

9. An apparatus for controlled closure of at least one clip around a filling material-free plait portion of a tubular casing at the end of a filling material portion enclosed by the casing comprising a closure device which closes the at least one clip in embracing relationship with the plait portion and a casing supply device from which the casing is withdrawn when filling successive filling material portions with a moved product flow of the filling material, the apparatus comprising:

a sensing device capable of sensing the withdrawal movement of the casing out of the casing supply device between two successive closure operations over at least one of a short period of time and a short length portion and capable of forming a corresponding sensing signal;

a controller capable of forming a control signal from the sensing signal operatively connected to the sensing device;

the closure device being connected to a drive device for jointly moving the closure device in substantially parallel relationship with the advance movement of the product flow controlled by the control signal.

10. The apparatus of claim 9 where the control signal is proportional to at least one of the withdrawal speed of the casing and the advance speed of the product flow.

11. The apparatus of claim 9 where closure of the at least one clip around the plait portion is effected during the synchronous joint movement of the closure device with the product flow upon filling of the filling material portion.

12. The apparatus of claim 9 further comprising:

a drive device for at least one displacer device, with which the displacer device is jointly moved in substantially parallel relationship to the advance direction of the product flow in dependence on the sensing signal from the sensing device.

13. The apparatus of claim 9 where the closure device and the displacer device are moved back into their starting positions after the termination of the clip closure operation by their associated drive devices.