The invention relates to a weighing device for a packaging machine, as generically defined by the preamble to claim 1.
DE 100 01 068 C1 has already disclosed a device for metering and dispensing powder into hard gelatin capsules or the like. As tamping pins descend into bores, they compress the powder, which is to be packaged, into pellets. In order to be able to obtain information about the mass of the pellets, means are provided that detect the spring path of the tamping pin directly preceding the ejecting pin.
In the capsule filling machines currently in use, usually the capsules are weighed after being filled, i.e. the combined weight of the capsule and filling (gross weight) is determined in order to check whether the filling quantity is correct. There are several methods for accomplishing this, e.g. weighing with a scale, weight determination through other physical effects, etc. using the statistical method or up to 100%. This method is imprecise due to a significant variance in weight of the empty capsules. There are also known methods in which the net weight is determined by a gross minus tare calculation. In these methods, capacitive physical effects are used, an approach that involves significant inaccuracies that are contingent on the system.
The object of the present invention is to eliminate or at least mitigate the above-mentioned disadvantages. This object is attained by the defining characteristics of the independent claims.
The device and method according to the defining characteristics of the independent claims increase the precision of the weight determination since they make it possible to eliminate imprecise capacitive methods for net weight determination. In addition, the capsules can be reliably and quickly removed, for example for weight determination, since at least one transport pin acts on the underside of the capsule and serves as a support during the removal of at least one capsule.
Other suitable embodiments ensue from additional dependent claims and the description.
An exemplary embodiment of the invention is shown in the drawings and will be explained in detail in the subsequent description.
A machine for filling and closing capsules 30 composed of a capsule bottom and a cap slid onto it has a twelve-part advancing wheel 20 that is rotated in steps around a vertical axis, with the individual handling devices situated at the stations 1 through 12 along the circumferential path of the wheel. At 1, the empty capsules 30 to be filled are loaded in a randomly ordered fashion, aligned, and then placed in an ordered fashion onto a capsule holder 21 of an advancing wheel 20. The capsules, which are still closed, are then removed from the capsule holder 21, weighed by a weighing device 22, then placed back into an empty capsule holder 21, and then the caps are removed from the bottoms. At 5, the filling, e.g. a powdered pharmaceutical product, is dispensed into the capsule bottoms. At 6, a weight testing system 16 checks the filling that has been dispensed into the capsule bottoms. At station 8, the capsules 30 are closed again. At 9, the gross weight of the filled capsules is determined by an additional weighing device 26. At 10, the capsules 30 are sealed, and at the subsequent station 1, they are ejected.
The invention describes how empty capsules 30 that are still closed can be removed from the capsule holder 21, weighed on a gravimetric scale 22, then placed back into an empty capsule holder 21, and taken apart. This device makes it possible to remove empty capsules 30 and replace them at full machine speed, without a loss of any consequence in output. It is possible to use a gravimetric measurement method to carry out a tare weighing of the capsules 30. If the additional weighing device 26 for filled capsules 30 is integrated into the capsule transport, it is then possible to determine the net weight based on the tare weight and the weight of the full capsules 30. Such a combination of a gravimetric tare weighing and a gross weighing to statistically determine the net weight is particularly well-suited to an intermediate capsule filling device. In addition, such a system is also capable of calibrating a 100% weight testing system 24 on another physical basis (e.g. X-ray).
In the synchronously functioning capsule filling machine, the capsule holder 21 filled with capsules 30 arrives for the removal of the capsules 30 as part of the weighing at station 3. The capsule holder 21 is composed of openings into which the capsules 30 to be transported have been placed. Transport pins 44 are situated underneath these openings and are able to move vertically toward the underside of the capsules 30. In station 3, the capsule holder 21 and the transfer device 42 are situated so that the vacuum openings 40 of the transfer device 42 cover the capsule tops.
As shown in
The transfer device brings the capsules 30 into alignment with a weighing dish 46 of the weighing device 22. The transfer device 42 lowers all of the capsules 30 into the corresponding openings of the weighing dish 46 (
The depositing of the capsules into the weighing dish 21 occurs in a fashion analogous to the removal procedure. It is also possible to supply vacuum to the openings that accommodate the capsule bottoms as the capsules 30 are being deposited into the capsule holder 21. This is to provide an improved fixing when the transfer device 42, in the process of depositing of the capsules 30, moves upward away from the deposited capsules 30. The vacuum supplied to the capsule bottoms can also be used to open the capsules 30 if the vacuum is provided to the vacuum bores 40 in parallel with the upward movement of the transfer device 42. This results in the opening of the capsules 30.
The transfer process described above in connection with station 3 is also used at station 9. The additional weighing device determines the gross weight of the filled capsules 30. Based on the tare weight of the capsules determined at station 3, it is possible to determine the net weight of the filling that has been dispensed into each capsule 30.
Number | Date | Country | Kind |
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10-2005-057-393.2 | Nov 2005 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP06/67914 | 10/30/2006 | WO | 00 | 5/16/2008 |