Stacking station for a thermoforming plant, method for producing cup-shaped products and thermoforming plant

Abstract

The invention relates to a stacking station for a thermoforming installation, to a method for producing cup-shaped products in a thermoforming installation and to a thermoforming installation equipped therewith. Ejecting products out of a film plane onto an additional conveyor belt using a pusher is known. The additional conveyor belt first brings the products to a tilting device. After actuation of the tilting device, the products lie on their side and are conveyed onward from there. The present invention provides first pre-stacking the products coming from the ejector, to then tilt them, preferably by way of their own weight, and to stack them only once they are lying.

Claims

1. A stacking station to stack thermoformed cup-shaped products formed from a continuous film strip in a thermoforming installation comprising: an ejector that ejects the cup-shaped products from an index; a pre-stack conveyor situated below the index, the pre-stack conveyor receiving the cup-shaped products ejected from the index to form pre-stacks of the cup-shaped products; a tilting device situated downstream of the pre-stack conveyor and comprised of a tilting edge adjacent to the pre-stack conveyor, the tilting edge tilts the cup-shaped product from a pre-stack orientation to a stacking orientation; a drop shaft situated adjacent to the tilting edge of the tilting device, the drop shaft receiving the tilted cup-shaped products from the tilting device, the drop shaft including walls, a stack floor, and a fall brake that slows down the tilted cup-shaped products via friction falling through the drop shaft from the tilting edge to the stack floor; and a deflector device situated in the drop shaft, the deflector device being activated to discharge a row of the cup-shaped products if one of the cup-dash shaped products does not fulfil quality requirements.

2. The stacking station of claim 1, wherein the ejector includes at least one ejector arm that engages the cup-shaped products to eject the cup-shaped products from the index.

3. The stacking station of claim 1, wherein the cup-shaped products are formed from an index into stacks, wherein the cup-shaped products in the index are arranged in columns that are substantially parallel to a machine direction of the stacking station and in rows that are substantially perpendicular to the machine direction of the stacking station.

4. The stacking station of claim 3 further comprising a pusher situated below the pre-stack conveyor and a removal conveyor situated adjacent to and downstream of the pusher.

5. The stacking station of claim 4, wherein the pusher pushes the tilted cup-shaped products from the stack floor of the drop shaft to the removal conveyor to form stacks of the cup-shaped products.

6. The stacking station of claim 5, wherein the pusher includes a first pushing stage that has a shorter feed motion to stack the pre-stacks from the pre-stack conveyor and a second pushing stage that has a longer feed motion to push the products onward for further transport.

7. The stacking station of claim 6, wherein the pusher includes a pushing finger for each column of cup-shaped product, wherein the pushing finger for each column enters a corresponding column of the drop shaft to transport the cup-shaped product on the stack floor in the machine direction of the stacking station.

8. The stacking station of claim 7, wherein the stack floor and the pushing fingers are tilted at an angle with respect to horizontal.

9. The stacking station of claim 1 further comprising a stacking line connected to the drop shaft, the stacking line being titled upward in a machine direction of the stacking station.

10. The stacking station of claim 9, wherein the stacking line includes a pushing brake that slows down the cup-shaped products pushed by the pusher.

11. The stacking station of claim 1, wherein the drop shaft includes a column for each column of each of the cup-shaped products in the index.

12. The stacking station of claim 11 further, wherein each column of the drop shaft includes lamellas attached to the walls that prevent the cup-shaped products falling through the drop shaft from inadvertently tilting forward.

13. The stacking station of claim 12, wherein the drop shafts are arranged as exchangeable modules.

14. The stacking station of claim 13, wherein the cup-shaped products fall through the drop shaft via gravity.

15. The stacking station of claim 14, wherein the stack floor and the drop shaft are tilted at an angle with respect to horizontal.

Description

(1) In the following, the invention is explained in more detail based on exemplary embodiments with reference to the drawings.

(2) FIG. 1 schematically shows a lateral view of a stacking station of a thermoforming installation, with an ejector, a plurality of products, a film, a pre-stack conveyor belt, a pusher, a tilting edge, a drop shaft, a pusher and a stack conveyor belt,

(3) FIG. 2 shows the schematic view of FIG. 1 after a first ejection cycle,

(4) FIG. 3 shows the view of FIGS. 1 and 2 during a second ejection cycle,

(5) FIG. 4 shows the view of FIGS. 1-3 after the second ejection cycle,

(6) FIG. 5 shows the view of FIGS. 1-4 during a third ejection cycle,

(7) FIG. 6 shows the view of FIGS. 1-5 after the third ejection cycle,

(8) FIG. 7 schematically shows a three-dimensional view of a part of the stacking station,

(9) FIG. 8 shows an exemplary embodiment of a module with a plurality of drop shafts.

(10) In the schematically shown thermoforming installation, a particularly preferred method according to the invention runs as follows:

(11) A forming tool (not shown) is disposed upstream of the stacking station 2 in the machine direction 1, i.e., in a simple linear construction of a thermoforming installation, to the left of the longitudinal extension shown in FIG. 1.

(12) The forming tool is a cavity tool, which is arranged to produce three rows of products in an index 3 in the machine direction 1, i.e. a product C of a first row, a product B of a second row and a product A of a third row. The number of columns of the index is discretionary. To simplify matters, since the view shown here is a lateral view, only one product and not an entire row or several products will be spoken of herein, since only the product, in the present example located entirely to the right of a row of the index, can be visibly shown in a lateral view.

(13) The produced products A, B and C are joined with each other by small notches 4, so that they can be transported through the installation beyond the thermoforming station while still being joined with a film 5

(14) Due to the fact that also a plurality of indexes are connected in the machine direction, the indexes run under an ejector 6 while being connected. The ejector 6 has respectively one ejection arm 7 (exemplarily labeled) for each row in the index, i.e. here for product A, for product B and for product C. The three ejector arms 7 are connected to each other by way of an ejector bridge 8.

(15) The installation clocks its feed motion in accordance with the length 9 of a single piece, i.e. the length of the products of an index produced in the forming tool during one stroke and one cycle.

(16) As soon as the film 5 with the single piece 9 and thus the three rows of products A, B and C has arrived in the ejector 6 and has stopped there, the ejector 6 moves downward with its ejector arms 7. In doing so, each of the ejector arms 7 reaches into its associated product A, B or C. Thereby, the notches 4 are ripped by the traction force induced therein and the products A, B, C detach from the film 5 thus forming single pieces. Only the residual film grid 10 remains downstream of the ejector 6.

(17) A pre-stack conveyor 11 is located below the level of the film 5 and of the residual film grid 10 on the level of the ejector 6.

(18) The stroke of the ejector 6 is adjusted such that the products A, B, C are ejected onto the pre-stack conveyor in the same constellation and come to rest there in the same arrangement relative to each other as within the index 3.

(19) Once the three products A, B, C have arrived on the pre-stack conveyor 11, the conveyor advances one cycle in the machine direction 1.

(20) However, while the film 5 is fed forward at each cycle by an amount corresponding to an entire single piece, in the example shown here, to the length 9 of the single piece with three products, respectively three cavities in the forming tool, the pre-stack conveyor 11 moves synchronously but only carries out a feed motion in the machine direction 1 that corresponds to the length 12 of a cavity, thus of respectively only one product A, B, C.

(21) The ejector 6 moves back upwards, the film 5 advances by the length 9 of a single piece and one cycle is ended (shown in FIG. 2).

(22) In this state, the foremost cup-shaped product C is still located on the pre-stack conveyor having advanced by one stroke of a length 12 of a cavity. The pre-stack conveyor is positioned in such a manner that there is still a little more space downstream, in the machine direction 1, of the ejected products A, B, C, than the length 12 of a cavity, so that the foremost product C can still rest safely on the pre-stack conveyor 11, because its center of gravity is still upstream, in the machine direction 1, of a tilting edge 13.

(23) The pre-stack conveyor 11 is adjustable both in the machine direction 1 and in its inclination relative to the horizontal. This allows precisely adjusting to what extent a foremost product C is still lying on the pre-stack conveyor 11 after one feed motion cycle or whether it has for example already fallen over the tilting edge 13.

(24) At the beginning of the second cycle (shown in FIG. 3) the ejector 6 again carries out an ejection stroke and ejects three identical products A, B, C out of an identical index in the film 5, concretely out of the residual film grid 10 thus formed.

(25) The ejector 6 is controlled in such a manner that it does not exert a vertically downward coercive force as far as the pre-stack conveyor 11. The reason for this is that the place for the two front products B, C of the index 3, in which the ejector 6 would eject the two front products B, C from the film 5, is already occupied by respectively one product, namely the two rearward products A, B. The consequence thereof is that the rearmost product A is ejected directly onto the pre-stack conveyor 11 as a result of the feed stroke of the pre-stack conveyor 11 but that the middle product B is pushed into a once rearward product A, located below it, having advanced as a consequence of the feed stroke; similarly the respectively forward product C is ejected downward out of the film 5 into the once middle product B after its displacement. This results in a single product, formed by the respectively rearmost product A, as well as two first pre-stacks 14, 15 and, in the start-up phase of the installation, an additional single product located downstream, namely the very first advancing product C (shown in FIG. 3 until now), being located on the pre-stack conveyor.

(26) In order to end the cycle, the ejector 6 moves back upwards and the pre-stack conveyor 11 again carries out a feed motion by the length 12 of a cavity in the machine direction 1.

(27) The respectively foremost pre-stack 16 (shown in FIG. 4, wherein the drawn representation is however based on a longer installation feed motion) is conveyed by the pre-stack conveyor 11 in the machine direction over the tilting edge 13. As a consequence of the weight of the respectively foremost pre-stack, the pre-stack tips over into a drop shaft 18 in a tilting direction 17 (indicated in FIG. 4). Walls 19 (exemplarily labeled) of the drop shaft 18 stabilize the products in the respectively foremost pre-stack during its tilting and falling motion in the drop shaft 18 until the falling pre-stack comes to lie on a stack floor 20. Thus the products A, B, C lie on the stack floor 20 in the tilted direction, therefore with a rather flat-lying or even horizontally oriented product axis 21.

(28) A pusher 22 is provided on this third level of transport of the product. It can be displaced forward parallel to the stack floor 20, namely in the machine direction. That way, it can push a first pre-stack into a second pre-stack, so that either a finished stack or an enlarged pre-stack 23 is formed (shown in FIG. 5).

(29) Any number of pre-stacks can be amassed on the stack floor 20 until a stack 24, to be transported out of the stacking station, is ultimately formed. The finished stack 24 is then pushed by the pusher 22 onto a removal conveyor 25, so that the finished stacks can be transported in the machine direction 1 out of the stacking station.

(30) If it is determined during production that a product located in an index 3 does not fulfill quality requirements, a deflector device, located for example in the drop shaft 18, can be activated and the row of products is discharged, wherein, in such a case, the pre-stack conveyor 11 preferably does not carry out its feed motion in the cycle; or the pre-stack conveyor 11 is activated against the machine direction 1, so that a waste product can be removed in a discharging direction 26 (indicated in FIG. 6).

(31) It has already been explained that the previously described, particularly preferred process sequence according to the invention (shown in FIGS. 1-6) preferably takes place simultaneously for all products of a row 27, 28, 29 of an index 3, so that in the case of three columns 30, 31, 32 of a row 27, 28, 29 for example, three drop shafts 33, 34, 35 can be provided, in order for the products of each column 30, 31, 32 to separately fall into respectively one drop shaft 33, 34, 35 (shown in FIG. 7), wherein also one pusher with three pushing fingers 36, 37, 38 is preferably provided, in order for each pushing finger 36, 37, 38 to be able to enter exactly one drop shaft 33, 34, 35 and to transport the products on the stack floor 20 onward in the machine direction.

(32) As shown in FIG. 7, the entirety of the drop shafts 33, 34, 35, together with the stack floor 20 and the pushing fingers 36, 37, 38, can be tilted at an angle 39 relative to the horizontal. However, they do not have to be inclinable, and/or the angle 39 can amount to zero or it can be negative, i.e. with a descending slope.

(33) The various drop shafts are preferably provided with sheet metal lateral walls 40 (exemplarily labeled, see FIG. 8).

(34) Downstream of a tilting edge 41 the products can thus fall downward between the lateral walls in a safely guided manner onto the stack floor 42. Resilient and ribbed lamellas 43, which are attached to the lateral walls 40, preferably at various heights, secure the products against inadvertently tilting forward in the machine direction 1. The lamellas 43 are preferably attachable, by means of mounting devices disposed in a grid-like manner, such as e.g. the holes shown here, so as to be displaceable in the machine direction 1, so that they can be disposed in a respectively targeted manner for various lengths of stacks.

(35) The lateral walls 40 of the drop shafts are preferably connected to each other, for example by way of a continuous screw, so that all the drop shafts can be exchanged as a module.

LIST OF REFERENCE NUMBERS

(36) 1 machine direction 2 stacking station 3 index 4 notch 5 film 6 ejector 7 ejector arm 8 ejector bridge 9 length of a single piece 10 residual film grid 11 pre-stack conveyor 12 length of a cavity 13 tilting edge 14, 15 first pre-stacks 16 foremost pre-stack 17 tilting direction 18 drop shaft 19 walls 20 stack floor 21 product axis 22 pusher 23 enlarged pre-stack 24 stack 25 removal conveyor 26 discharge direction 27, 28, 29 rows 30, 31, 32 columns 33, 34, 35 drop shafts 36, 37, 38 pushing fingers 39 angle 40 lateral wall 41 tilting edge 42 stack floor 43 lamellas