Material or article handling – Apparatus for moving intersupporting articles into – within,... – Stack forming apparatus
Reexamination Certificate
2000-11-01
2002-08-27
Lillis, Eileen D. (Department: 3652)
Material or article handling
Apparatus for moving intersupporting articles into, within,...
Stack forming apparatus
C414S798400, C414S798900
Reexamination Certificate
active
06439828
ABSTRACT:
The invention relates to a method and an apparatus for receiving mass-produced articles or products for stacking, especially plastic cups, which after having been formed in a moulding and/or punching machine are ejected from same. The apparatus comprises a catching device assigned to the machine for receiving the products after they leave the machine and a stacking and holding device located downstream of the catching direction, in which the products are received and after stacking held ready for further transport. The catching and the stacking and holding devices are capable of being moved towards one another and away from one another. The invention relates further to a stacking and holding device suitable for use in the receiving apparatus, which comprises at least one stacking channel and one or more claw elements which run parallel with the stacking channel, surround the latter and are provided on their inner side facing the stacking channel with one or more gripping pawls adjustable rotationally and/or translationally for the grasping of mass-produced articles, especially plastic cups. The invention relates further to a gripping pawl suitable for use in the stacking device, which possesses an inner side assigned to a product or item for stacking and a rearward outer side, wherein there are formed on the inner side one or more undercuts, steps or depressions as claw elements or shear means for the product or item for stacking.
In the manufacture of plastic cups by the deep-drawing process, the use of polystyrene as a material is known. The latter is increasingly being replaced by polypropylene, which is available as a low-price material, but is more difficult to process. An article made from the latter does not acquire its final strength until hours after its manufacture. It is therefore particularly important that the “soft” articles ejected from the machine are as far as possible protected against mechanical forces in the axial and radial direction during the subsequent stacking operation.
For the producing of deep-drawn parts of such thermo-plastic material, in particular cups or other receptacles, an apparatus for the moulding, punching and stacking of said parts is known (German utility model 91 08 344.3). After the moulding of the plastic part the mould is opened and the plastic part is pushed into a stacking apparatus. In order to ensure a reliable transfer of the articles into the stacking apparatus, the mould is swivelled and opened, and the stacking apparatus is moved towards the Mould. It is disadvantageous here that the last plastic part ejected, which is still hot and therefore easily deformable, has to displace axially the plastic parts already stacked within the stacking apparatus. Hence a deformation of the last part ejected and received in the stacking apparatus is easily possible. For example, deformed plastic parts of an oval shape can be printed on later only with difficulty, since they can cause friction in the printing machine, something which causes fault messages.
DE 36 24 638 C2 discloses a retaining apparatus for a stacking channel, in which lids for plastic receptacles are held by means of guide rods bounding the stacking channel. The retaining apparatus is distinguished by pawls which are integral with the guide rods and are spring-mounted radially by means of compression springs. The front side of the spring-mounted pawls faces the inside of the stacking channel and consists of flat flanks which are arranged in saw-tooth-like sequence, such that there form in the area of the deeper parts of said flanks projections running in transverse direction for the edges of the lids to be held. However, the projections lie diametrically opposite one another so that bottlenecks are formed which lead to a distortion of the lids. Moreover, nothing is disclosed as to how the lids are transferred out of a mould and introduced into the stacking channel. A further disadvantage consists in the fact that the last lid to arrive in the stacking channel has to give a push to the preceding lid, which reduces the dimensional stability considerably, since a strong mechanical pressure is thereby exerted on the last lid introduced, which is still hot and hence deformable.
DE 32 37 943 A1 discloses a magazine for the stacking of paper articles, in which there are arranged on at least one guide side of the magazine, as guide surfaces, oblique surfaces succeeding one another after the manner of scales. The oblique surfaces constrict the guide shaft in the guide direction and are intended to prevent the thin sides of the paper articles, for which a wedge shape is assumed, preceding the thick sides in the guide direction. Here again nothing is inferable about the take-over of the paper articles out of a mould or similar.
DE 44 36 531 C1 discloses a method for converting particles formed and punched out of a thermo-plastic film in several rows into single-row stacks. Cups formed out of thermo-plastic film are placed in receiving spectacles by means of a vacuum transfer device. The receiving spectacle is displaced in flow direction by one row interval and then moved back again. Apparently, however, the stacks can reach only a height of three cup units.
A receiving apparatus roughly of the kind mentioned in the preamble is known from the German patent DE 195 09 057 C2. In the latter a sub-division into two steps of the transfer movement from the mould to a stacking conveyor belt is proposed, by means of which the movement time per step is,to be reduced In the first step the plastic parts, for example cups, are pushed and sucked out of the opened mould onto a first receiving plate. By swivelling of the first catching or suction plate the cups arrive with the bottom foremost at a second suction plate, where they are sucked once again. They are further blown away from the first catching or suction plate by a short blast of compressed air. While the first catching or suction plate is being swivelled back again, the second suction plate is displaced linearly together with the cup sucked on the bottom side and is lowered to an extent such that the cup may be deposited on an already assembled stack of cups. This poses an additional requirement in control terms, however, namely that the vertical movement of the second suction plate has to be reduced from one cycle to the next, because the stack grows in its height. The swivelling of the first catching and suction plate also poses an additional requirement in construction terms. It is a further complication that the movements of the first catching and suction plate and of the second suction plate have to be coordinated or synchronised with one another, which leads to further control requirements.
The invention is based on the object of further developing a receiving method and a receiving apparatus of the kind mentioned in the preamble, while at the same time avoiding the above-mentioned disadvantages, in such a way that through careful handling of the plastic products ejected from the mould a simplification in the sequence of movements and in the equipment design is achieved. In particular the number of the transfer stations between plastic mould and stacking site and of the drive components required is to be reduced. In addition, a considerable simplification of the sequence control of the transfer components which grasp the plastic products is to be aimed for. Finally, the reliability of the taking over of the plastic products out of the mould and their stacking in the operating sequence is to be increased, in the course of which the plastic products are to be handled in a careful manner.
In order to solve this set of problems, it is proposed in the case of a receiving method for instance of the kind mentioned in the preamble that the stacking and holding device be used during the movement towards one another to grasp the product or products as they leave the catching device and during the movement away from one another to withdraw the product or products out of the catching device. The practice conventionally adopted in the prior art
Lillis Eileen D.
Lowe Michael
Pandiscio & Pandiscio
LandOfFree
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