Package making – Methods – Closing package or filled receptacle
Patent
1992-10-08
1994-06-21
Culver, Horace M.
Package making
Methods
Closing package or filled receptacle
53 53, 53 75, 53 77, 53317, 533315, B67B 320, B67B 326, B65B 728
Patent
active
053219350
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a slewing device for screw closures, in particular, from plastic materials, for containers and comprising a drive and a torque limiter for controlling power supply to the drive and including a torque sensor and an angle of rotation sensor, and a method of placing screw closures on containers using the slewing device according to the invention.
A slewing device for screw caps or screw closures as well as a method for putting such closures or caps on containers are known (DE-OS 37 15 935). The known slewing mechanism serves for screwing screw caps onto receptacles and observe herein a preset closing moment. A torque limiter prevents exceeding the desired moment. For this purpose a control circuit measures the drive current absorbed by the drive motor of the rotational device and triggers control signals if the current rises to a specific value corresponding to a specific torque of the threaded-on cap or closure, by means of which the drive current of the drive motor is interrupted. Thus one directly affects the energy supply of the drive.
However it was seen that in some cases especially when using solid plastic closures, a secure sealing of the container is not achievable also when presetting a specific closure moment. This applies especially when containers or bottles subjected to an overpressure are to be closed. By presetting a specific closure moment it is in addition possible to damage the mouth region of the container to be closed, especially with glass bottles, which leads to danger for the consumer. Finally it is seen, that the opening moment, meaning torque required for initial opening of the container, is often considerably higher than desired.
It is therefore the task of the invention to create a slewing mechanism as well as a method, by means of which containers with screw closures, especially also those made of plastics material, can be closed, wherein containers subjected to overpressure are closed in a pressure-tight manner however without being damaged in the mouth region and where a specific opening moment is set up.
SUMMARY OF THE INVENTION
This task is solved in a slewing mechanism in which the torque limiter determines the angle of rotation only after a predetermined closing torque is reached. Since the control arrangement or the torque limiter determines to begin with by means of a torque sensor whether a specific closure moment, the application or applied moment, is reached during a closure process, a defined point of departure or point of reference for the additional measurement during the closure process is established. After reaching this application moment the angle of rotation is acquired, through which the screw closure is turned by the slewing mechanism. A particularly sensitive closure of the container is assured by acquisition of the angle of rotation after reaching the application moment. This permits to exclude damage to the mouth area with a high degree of certainty and to assure a very precise observation of a desired opening moment.
In a preferred embodiment of the slewing mechanism or device the control arrangement is laid out in such a way, that the angle of rotation through which the screw cap or screw closure continues to be turned after reaching a predetermined application moment can be limited to a presettable value. This layout of the slewing device results in a particularly sensitive adjustment of the desired closing moment, wherein the predetermined opening moment can be observed very accurately.
In a preferred embodiment form of the slewing mechanism the torque acting upon the screw closure is acquired by means of the control arrangement serving as torque limiter. Herein the current fed to the drive or the voltage applied to the drive of the slewing device is registered. Since the power absorbed by the drive is proportional to the voltage or to the current, the momentary torque can be determined from the momentary value of the current or the voltage. This determination of the moment is particularly easy to
REFERENCES:
patent: 4535583 (1985-08-01), Tanaka et al.
patent: 4614077 (1986-09-01), Muto et al.
patent: 4616466 (1986-10-01), Tanaka et al.
Schwarz Wolfhard
Spatz Gunter
Alcoa Deutschland GmbH
Culver Horace M.
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