GB2278590A - Stacking apparatus - Google Patents

Description

2278590 STACKING APPARATUS The present invention relates to stacking

apparatus for stacking articles of thermoplastic plastics material expelled from a production tool, such as a moulding tool or a punching tool.

In the case of stacking apparatus described in DE-PS 34 39 660, articles expelled from a production tool are entrained by suction by a plate and, optionally after pivotation, are transported directly into horizontally disposed stacking grooves. The end position of the plate on delivery of the articles is the same with each cycle, i.e. an article transported into a stacking groove pushes the partly formed stack in front, thereof one place further on. However, this is disadvantageous because the article must absorb the entire force for pushing on the stack. There exists a risk of deformation of the articles, which in fact are still relatively warm. According to the respective angle of the side walls of beaker-like articles there is also the risk of jamming of one article in the other if suitable stack protrusions are not provided. In the case of flat articles, the foremost articles tend to drift out or fall over. As, with beakerlike articles, each delivered article must impinge precisely in the preceding article, this must be fixed in its delivery position and should not tip, otherwise the base of the article will strike the rim of the previously stacked article. This has to be achieved by way of spring- loaded pressure members or brushes which keep the stack together, as a result of which the force required for displacement of the stack is higher.

- 2 In apparatus disclosed in DE-OS 20 16939 articles of plastics material are removed from a film strip and placed one above the other on a transport belt. By this measure problems arising from the onward transport of the stack by way delivered article are indeed avoided, but it is not evident from this document how the individual articles are placed on top of one another and whether the transport rocker, with suction device, present in the apparatus executes different pivot angles. This, in fact, is excluded, because a different pivot angle viewed horizontally - would have the consequence of 4 different spacing of the suction device relative to fixed fulcrum. The stacked articles would then not come to lie cleanly one above the other. There is left to this apparatus only the possibility of executing a constant pivot angle and leaving the articles to fall onto the transport belt or onto the articles already stacked thereon. Stacking damage frequently occurs in such free falls.

There accordingly remains a need for apparatus which may be able to undertake reliable take-over, transport and stacking of articles without risk of deformation or jamming thereof and without giving rise to drifting apart of the formed stack.

According to the present invention there is provided stacking apparatus for stacking articles of thermoplastic plastics material expelled from a production tool, the apparatus comprising a receiving device for seizing of such expelled articles, means for displacing the receiving device into a delivery setting, and a drive which, in the delivery setting, executes per delivery cycle a stroke reduced by the spacing between the stacked articles starting out from a maximum stroke and until a predeteremined number of articles per stack is reached, and which then repeats such stacking cycle.

Because the device is moved by an appropriate drive, the articles can be picked up and, after transport into the delivery setting, placed directly into the previously transported article, but with prior adaptation of the device stroke to the predetermined spacing 5 between two successive articles. The articles, for example containers, can be inserted into one another with positional accuracy and held until in the release position, so that no path is covered in free fall. In the case of re-equipment of an associated production tool, such as a thermal moulding machine, for production- of another 10 type of article, a rapid adaptation of the apparatus to this new article may be possible in simple manner and without great cost with respect to the article shape, article spacing in the stacked state and number of articles in the stack before this is moved on. The apparatus can be of simple construction' and, for the article retention, may require only a simple format element which can be quickly exchanged.

An embodiment of the invention will now be more particular described with reference to the accompanying drawings, in which:

Fig. 1 is a cross-sectional view of stacking apparatus embodying the invention, in which a receiving device is shown shortly before pick up of articles; Fig. 2 is a view similar to Fig. 1, but in which the device is shown shortly before delivery of an article; Fig. 3 is a plan view of the apparatus in the direction of arrow X in Fig. 1; and Fig. 4 is a view, to an enlarged scale, of two such articles in a stack.

Referring now to the drawings, there is shown stacking appara,' us comprising a stationary frame 1 which, for reasons of clarity, is shown only in part. A carrier 3 is arranged on the frame to be pivotable about a shaft 2 between a take-over or receiving setting illustrated in Fig. 1 and a delivery setting illustrated in Fig. 2, pivotation being effected by way of a link 6, which is articulated to the carrier 3, and a crank 5 driven by a motor 4. Two columns 7 are guided in the carrier 3 and are connected together at their lower ends by a transverse yoke 8. A plate 9, which carries article receivers 10, is seated on the yoke 8. The plate 9 and receivers 10 constitute format elements which are dependent on the particular articles to be stacked, these irticles being illustrated in the figures as containers 11. The format elements can also be represented by a flat plate, which is connectible to a vacuum source and 'entrains the articles by vacuum. Suction of the articles by way of vacuum, which in the case of the illustrated embodiment is produced by sucking away air through bores 12 and 13, is the simplest method of seizing the articles.

Each of the columns 7 is provided along one side thereof with a toothing in which a respectivegear 14 meshes. The two gears 14 are seated on a shaft 15, which is mounted on the carrier 3 and driven by a drive 16, which is similarly mounted on the carrier and which preferably has the form of a servomotor. The drive 16 is so constructed that it allows a very precise positioning, in which connection the rotational angle thereof and thus the position of the yoke 8 can be readily varied from the apparatus control by way of prior inputting.

The apparatus receives a row of containers 11 expelled from a moulding/punching tool 17 in that the yoke 8 with the plate 9 and receivers 10 is suitably brought into position in front of the container openings by pivotation and, if required, travel by way of the drive 16, and vacuum is applied. The thus seized containers 11 are then transported into the vertical setting shown in Fig. 2. Then lowering of the yoke 8 takes place, by the amount "All in the case of the first container 11 of a new stack, until that first container rests on a transport belt 18. The vacuum is now relieved and the yoke 8 travels upwards again. After take-over of the next row of containers and pivoting of the carrier the yoke is lowered by a stroke length which is maller than the previously executed stroke length 'W' by the amount "H", which corresponds to the spacing between two adjoining containers in the stack. The' dimension "H" can be determined by appropriate stacking protrusions in the case of beakerlike articles. In the case of articles without stacking protrusions, for example flat plates, the dimension "H" is essentially determined by the thickness of the constituent material. In each such delivery phase the yoke executes a stroke smaller than the preceding stroke by the amount "H", until a stack 19 with a predetermined number of articles has been formed. The transport belt 18 is then advanced by an amount "B", so that a place for formation of a new stack is provided. In this manner the containers 11 are formed into a stack 19 cleanly, precisely and free of damage.

In the case of changing over of the apparatus, there is ii put into the apparatus control which starting dimension "A" the yoke 8 must execute, how large the pitch spacing "H" of articles in the stack is and how many articles shall form a stack. The control can then. compute the required stroke lengths. Apart from exchange of the plate 9 with the receivers 10, nothing further is required for a changeover.

f

Claims (4)

1 Stacking apparatus for stacking articles of thermoplastic plastics material expelled from a production tool, the apparatus comprising a device for taking over such expelled articles in successive take-over phases and delivering the articles in delivery phases alternating with the take-over phases to form stacks in stackforming cycles, displacing means to displace the device between a take-over setting in which the articles are seized in the take-over phases and a delivery setting in which the articles are released in the delivery phases, and drive means operable to so drive the device to execute a del,ivery stroke prior to article release in each delivery phase that the strokes in each stack-forming cycle correspond in number to a predetermined number of article's intended to form each stack and are successively reduced in length from an initial maximum valve by an amount substantially corresponding to a predetermined pitch spacing of the articles in such a stack.

2. Apparatus as claimed in claim 1, the drive means comprising a servomotor.

3. Apparatus as claimed in claim 1 or claim 2, the displacing means comprising a crank drive to pivot the device.

4. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.