Package making – Closing packages and filled receptacles – By means adapted to engage outturned seam of package cover
Reexamination Certificate
2002-05-21
2004-06-08
Rada, Rinaldi I. (Department: 3721)
Package making
Closing packages and filled receptacles
By means adapted to engage outturned seam of package cover
C053S469000
Reexamination Certificate
active
06745543
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for forming a packaging unit consisting of an endless hose or for sealing a prefabricated packaging unit, in particular a bag for loose material, said apparatus comprising an ultrasonic welding device including an anvil and a sonotrode, which are movable towards each other, and a means for positioning the hose material to be welded between the anvil and the sonotrode, The present invention additionally relates to a method for forming and/or sealing a packaging unit.
2. Brief Description of the Prior Art
An apparatus according to the generic clause as well as a method are described in the article “Verschlie&bgr;en mit Ultraschall” (“sealing with ultrasound”) of the applicant of the present patent application in the periodical “Verfahrenstechnik” 34 (2000), No. 12, pp. 12-13. This article describes various ultrasonic welding devices, e.g. for welding a valve bag in the area of its valve, said valve bag being first pushed onto a filler neck, filled with a loose material, and, subsequently, it is removed from the filler neck. These valve bags are prefabricated packaging units which are sealed in the above-described apparatus.
An ultrasonic welding device is, however, also known for forming a packaging unit consisting of an endless hose. In the so-called FFS (form-fill-seal) method a gusset-type hose or a hose without a gusset is unwound from a roll. A predetermined length piece is cut off from the endless material supplied, and sealed at the location of separation by conventional welding. The thus produced bag for loose material, which is open at the top, is first deposited in a place of intermediate deposit. Here, the weld cools down so as to achieve the strength which is necessary for the future filling of the bag for loose material. The prepared bag for loose material is then seized in said place of intermediate deposit and placed below a filling unit such that its opening faces upwards. After the filling operation, the material of the bag for loose material is welded also on the upper side of the bag. For this purpose, the above-mentioned prior art provides an ultrasonic welding device.
This known device used for carrying out the FFS method is, on the one hand, disadvantageous insofar as a place of intermediate deposit is required. On the other hand, the bag for loose material produced according to the FFS method has, at least on the lower side thereof, a length section of the hose material projecting beyond the lower weld at the end of the bag. It should be the aim of the method to produce the highest possible number of bags for loose material from the endless hose material supplied.
In the case of the above-described apparatus for sealing a valve bag after removal of said valve bag from the valve neck, the problem arises that particles, e.g. pigments or toxic particles, may adhere to the inner side of the valve. The particles located between the free end of the projecting valve and the weld may dust off during future handling. This cannot be desirable in the case of toxic substances. Paint pigments dusting off lead to a very intensive colouring of the surroundings, which is not desirable either.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide an apparatus of the type mentioned at the start, in the case of which the above-described problems do not exist. For the so-called FFS method, for example, an apparatus is to be provided by means of which the endless material supplied is utilized in the best possible way for producing the bags for loose material. In addition, particles adhering to the valve are to be prevented from dusting off. Hence, it is, in particular, the object of the present invention to further develop the apparatus mentioned at the start in such a way that it can be used for producing packaging units in the case of which length pieces projecting from the weld at the end of respective packaging unit are avoided as far as possible.
It is a further object of the present invention to provide a method in the case of which the endless material supplied is utilized in the best possible way for producing packaging units. Furthermore, the method aims at preventing particles, which adhere to the sealed packaging unit, from dusting off.
For solving the problem as far as the apparatus is concerned, the apparatus mentioned at the beginning is further developed by means of the present invention insofar as the anvil comprises two anvil parts which are movable relative to one another in the direction of the sonotrode, one of said anvil parts being implemented as a sealing anvil and the other part being implemented as a separating anvil.
By means of the apparatus according to the present invention, it is possible to effect sealing and, simultaneously, cutting off directly in, or adjacent to the weld produced by means of ultrasonic welding. The apparatus for sealing especially a valve bag, cuts off the free end, which projects beyond the valve bag, in or directly adjacent to the weld produced by means of ultrasonic welding. It follows that contaminations adhering to the outwardly open residual piece of the valve neck are removed, e.g. sucked off, together with the projecting end piece already at the filling station.
When forming packaging units, in particular bags for loose material, according to the FFS method, the endless material supplied is utilized in the best possible manner by means of the apparatus according to the present invention. The lower end of the bag for loose material is defined by the weld. A length piece of the hose material projecting downwards from said weld does not exist.
For simplifying the structural design of the apparatus according to the present invention, it is suggested that, in accordance with a preferred embodiment, the two anvil parts should essentially be implemented as plate-shaped components, and that the anvil parts should abut on one another with their neighbouring longitudinal sides. The relative movement of the two anvil parts is thus preferably guided via the neighbouring longitudinal sides.
Neat and reliable cutting off of the projecting valve piece as well as cutting off of the predetermined length piece from the endless hose supplied for forming an open bag are supported by the circumstance that the separating anvil is implemented such that it tapers in the direction of the sonotrode.
In particular in cases in which gusset-type hoses are used for producing packaging units, and for the purpose of sealing valve bags, it turned out to be advantageous when the sealing anvil is provided with a pressure surface extending parallel to the end face of the sonotrode, said pressure surface being provided with diagonally intersecting grooves which are distributed over the area thereof. The use of gusset-type hoses entails the problem that four layers have to be welded at the edges of the hose, whereas in the middle only two layers have to be welded. In particular at the transition from the two-layered to the four-layered area, the material of the packaging unit, which is preferably plastic material at least in the area of the weld, should be able to flow to such an extent that the differences in the wall thicknesses can be compensated for. This effect is preferably produced by grooves which are formed on the pressure surface in a diagonally intersecting pattern. The dimensions and the depth of the grooves depend on the thickness of the material used and on the nature of the packaging unit. The depth of the grooves increases when larger wall thickness are used.
In order to simplify the apparatus according to the present invention, it is suggested that at least the sealing anvil should be implemented as an integral component extending over the whole welding length. Surprisingly enough, it turned out that, even in the case of the FFS method, a gusset-type hose can reliably be sealed across its whole width by means of an apparatus having such a simple structural design.
The material to be sealed can be clamped prior to and
Dietrich Norbert
Dreier Hans Bernd
Tillack Bernd
Greif-Velox Maschinenfabrik GmbH
Laubscher, Sr. Lawrence E.
Paradiso John
Rada Rinaldi I.
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