DE4421870A1 - Stackable, thin-walled container - Google Patents

Abstract

A thin-walled stackable container (1) has several shoulders (8a to 8f). Each shoulder (8a to 8f) has a wall section (10) with a reverse tapering angle gamma of more than 3 DEG . The reverse tapering wall sections (10) end at their lower edge by a transition section (12), forming a supporting shoulder inside the container. The transition sections are joined to the reverse tapering wall sections at a sharp, outwardly oriented edge. The transition section has an even flat section (16) inclined in relation to the horizontal at an angle beta >/= 0, so that the flat section rises towards the inside of the container.

Description

The invention relates to a stackable, thin-walled container, in particular Plastic drinking cup usable in vending machines, the Circumferential wall at least in one area at an angle α in one A plurality of successive stages are extended upwards, each Step has a counter-conical wall section, the lower edge with the formation of a support shoulder inside the container Transition section passes. The invention also relates to a Process for manufacturing such containers and on a mold.

Such containers are known from DE 36 29 655 A1. If this mug not all levels of the inner cup are on the Stack the shoulders of the outer cup. Only when axial pressure is exerted all levels are on the stacking shoulders, the lower one The edge area of the steps, which previously rested, is elastically deformed. This results in an axial suspension and sometimes also Deformation of the cup walls, which can impair stacking safety.

Since the lower edge area of the steps is rounded, it can become one The steps slide off and jam the individual cups come when the walls are not stable enough. Stable Cup walls can only be achieved over a corresponding thickness, however endeavoring to manufacture cups weighing less than 3 g, opposes.  

Thin-walled cup-shaped containers are known from US Pat. No. 3,223,305, in which the cup wall rises in a plurality of steps expanded and each step at its lower edge one radially outwards projecting rim and one radially towards the inside of the container protruding annular shoulder forms. The training is like this taken that the peripheral wall portions of each stage are cylindrical and the lower edge ring of each stage in the manner of a piston ring in this cylindrical Wall is guided. These containers are designed in such a wall thickness that with the above dimensioning for 0.2 l container content Container weight of about 4.5 g to 5 g result. Despite this stable and high stack security training can be from the US-PS 3,223,305 known cup practically only by hand from a stack singularize because of those running in the cylindrical wall section Guide rings of air access to the inside of the cups to be separated is completed.

From DE-AS 11 36 599 stackable cups are known, which in their Upper part have a stacking step with a counter-conical wall part. The Stacking step has an annular protruding after the container interior Shoulder on which the inner cup with its stacking level rests. Below the stacking step, a holding part with support rings is provided, which for the stacking is of no importance due to the large distances between them to have.

In contrast, it is an object of the invention to provide a stackable thin-walled Containers, in particular one that can be used in vending machines for drinks Drinking cup to improve on its stacking device so that high Stack security with the ability to absorb significant amounts at one Container stack exerted axial pressures with significantly less weight Containers and the ability of automatic separation can be combined. It  is also an object of the invention, a method and a mold for Ready to manufacture such containers.

This object is achieved with a container according to the features of claim 1. The method is the subject of claim 10 and the molding tool is the subject of claim 13.

Due to the greater inclination of the counter-conical wall section a counter conicity angle γ of more than 3 °, preferably 3-6 °, at predetermined angle α of the peripheral wall a wider transition section formed than is the case with the containers according to the prior art is. The fact that the transition section is forming a sharp, outward-facing edge on the counter-conical wall section connects, a flat support of the steps is created, which the Stack security increased. With large axial forces acting on one Container stack act, so no axial slipping or jamming the container will take place more because all the touching stages are mutual get caught.

The transition section preferably has a flat plateau section, which preferably has an angle β 0 °, preferably 0-3 °, and thus runs horizontally or is inclined with respect to the horizontal. At at an angle of β <0, the plateau section rises inwards. The steps are thus designed in the form of an undercut, which offers the advantage that with axial forces acting on the stack of containers, the Plateau sections of the respective inner cup due to the inclination of the Do not slide plateau sections inwards but outwards. The individual stages can thus not against each other in the axial direction slip, which can lead to jamming of the individual containers. Each the larger the angle β is chosen, the easier it is to move axially Load the plateau sections, the counter-conical  Move wall sections towards each other so that the support area A enlarged.

The contact area A of the plateau sections is at least one third of the Width B of the plateau sections. With a large axial load and a large one Angle β can shift the plateau sections so far that the entire width B of the plateau section is used as a support area.

The individual steps with their counter-conical wall sections and the Plateau sections are preferably designed so that when Interlocking containers all plateau sections with the exception of the each upper plateau section of the inner cup on the Place plateau sections of the outer cup. With axial load thus the power is immediately absorbed by all levels.

The advantage of the container is that due to the design of the individual levels a high stability is achieved, which is also the collection large axial forces. It is therefore possible to change the wall thickness of the Make containers correspondingly thin without stack security affect. While conventional cups with a filling volume of 0.2 liters have a weight of 3.2 to 3.5 g, has one cup according to the invention with the same filling volume has a weight of less than 3 g, preferably 2.7 g. Accordingly, a weight reduction is also at smaller and larger containers with, for example, 150 cc or 250 cc Content possible. You achieve a clear material and Weight saving.

For the formation of strongly inclined counter-conical wall sections and sharp-edged steps, which leads to a kind of sawtooth structure, is also a new manufacturing process and a corresponding mold required. To achieve the sharp-edged formation of the steps is  provided according to the invention that during deep drawing in the interior of the container an overpressure and in the area of the lower edge of the counter-conical An additional vacuum is applied to the wall section of each step. As a result, the thermoformed film in the edge area of the steps becomes so wide pressed outwards so that sharp edges form. The choice of Vacuum and overpressure depend on the size of the thermoformed item and thus on the wall thickness of the film to be deep-drawn. It has found that for conventional cup sizes from 0.2 to 0.25 l content Overpressure from 4 to 8 bar and an additional underpressure from 0.5 to 1 bar, preferably 0.9 bar, the desired sharp-edged design of the steps guaranteed.

Because of the large number of stacking steps with the strong undercuts it is no longer possible to demold the containers in the usual way. Drinking cups are usually demoulded by floor ejectors. The work of Ejection force on the bottom of the cup would, however, in the inventive Containers to dent and thus damage the lower part of the Bechers lead because of the undercuts of the container in the area the steps in the molding tool are held back too much. The Processing shrinkage for the diameter of the named container is for example with polystyrene 0.2 to 0.4 mm. The undercut on one Angle γ of 6 ° and a width of the counter-conical wall section of approx. 4 mm is approximately 0.8 mm, i.e. at least twice the Processing shrinkage. The deep-drawn container is preferably subsequently deep drawing for ejection from the mold on its edge and grasped at its bottom. The forces acting on the container are thus distributed more evenly so that damage to the container is avoided can be.

The molding tool has corresponding counter-conical wall sections, which also has a counter-conicity angle δ of more than 3 °, preferably  from 3 to 6 °. The horizontal wall sections of the Molding tools are also preferably at an angle ε of 0 ° 0 to 3 °, inclined. While in the prior art air extraction holes in According to the invention, circumferential slots are provided in the area of the steps introduced in the mold, to which the additional vacuum is applied becomes. In the deep-drawing process, the film to be deep-drawn is corresponding to the applied pressures more or less pressed into the slots, so that sharp edges can form at the bottom of the steps.

The horizontal wall section preferably sits outwards in the lower boundary wall of the slot. So there are no paragraphs within the molding tool that the formation of the sharp edges on could hinder the lower end of the steps. The width of the slots is preferably 2 to 5 times the wall thickness of the deep-drawn container.

Not only a floor ejector is used to eject the deep-drawn containers provided, but also a scraper plate that has an annular Has projection for reaching under the container edge. Scraper plate and Floor ejectors are preferably moved uniformly, so that the to Demolding necessary forces evenly distributed over the entire container will.

Exemplary embodiments are described below with reference to the drawings explained in more detail.

Show it:

Fig. 1 is a side view of a drinking cup,

Fig. 2 shows the stepped portion shown in Fig. 1 with two nested containers in an enlarged scale;

Fig. 3a shows a vertical section through the die,

FIG. 3b shows a vertical section through a mold according to the prior art,

Fig. 4 is an enlarged view of the detail X and drawn in Fig. 3a

Fig. 5 is an enlarged view of the detail Y drawn in Fig. 3a .

In FIG. 1, a container in the form shown a drinking cup 1, the peripheral wall 3 from the tank bottom to the curled in the illustrated example, the upper opening edge 5 toward in three sections, namely a lower conical wall section 6, an upper smooth conical wall portion 7 and a middle step section 9 expanded. The two conical wall sections 6 and 7 have the same taper angle α of, for example, 9 °. The step section 9 has a total of six steps 8 a to 8 f. The number of stages can also be chosen to be larger or smaller.

In FIG. 2, the step portion 9 is shown of two nested cups 1 or 2 larger. The upper conical wall section 7 has an angle of inclination α, which in the example shown here is approximately 9 °. The angle α can be between 7 and 11 ° and, depending on the size and shape of the container, can also be larger or smaller. The step section 9 has the same inclination angle α overall. Each step 8 a to 8 f has a counter-conical wall section 10 a to d, 20 a to d with a counter-conicity angle γ, which is 6 ° in the example shown here. The counter-conical wall section 10 a to d, 20 a to d merges at the bottom via a sharp, outwardly pointing edge 14 into the transition section 12 , which is designed as a plateau section 16 . The plateau section 16 of each stage 8 a to 8 d is inclined downwards by an angle β, so that the plateau section 16 rises inwards. The angle β, which indicates the inclination with respect to the horizontal 18 , is 3 ° in the example shown here. The height H of the steps 8 a to 8 d and the width B of the plateau sections 16 are coordinated with one another taking into account the angles γ and β such that the cups 1 , 2 can be separated without mutual hindrance. When plugging into one another or singularly, the edges 14 can pass through the inner shoulders 15 unhindered.

The formation of the step 8 a to 8 d, taking into account the angle of inclination α is selected such that a bearing region A comes about, which is about half the width B of the plateau portion sixteenth When axial forces act on the cups 1 , 2 , the plateau surfaces 16 of the inner cup 1 slide on the plateau surfaces 16 of the outer cup 2 and shift outwards due to the angle of inclination β of the plateau sections 16 . Thus, the cups get caught under axial load and cannot slide against one another in the axial direction, with the result of damage to the peripheral wall. In extreme cases, the counter-conical wall sections 10 a to 10 d of the inner cup 10 can rest on the inner surfaces of the counter-conical wall sections 20 a to 20 d of the outer cup.

In Fig. 3a, the mold 30 is shown, which has a lower conical wall portion 34 and an upper conical wall portion 35 , the inclination angle tief is adapted to the angle α of the container according to the shape of the deep-drawn container. A stepped section with steps 36 a to 36 f is arranged between the lower and the upper conical wall sections 34 and 35 , each step 36 a to 36 f having a counter-conical wall section 37 . The conical angle δ of the conical wall section 37 is 6 ° and is adapted to the conical angle γ of the container. Accordingly, the horizontal wall portion 38 is formed of the steps 36 a to 36 f, the inclination of the wall portion 38 has an angle ε of 3 °. This can be seen in the enlarged illustration in FIG. 4. In the lower area of steps 36 a to 36 f, where the edges 14 of the container are to be formed, there are air extraction slots 39 a to 39 f, to which additional vacuum is applied during the deep-drawing process.

A floor ejector 31 and a scraper plate 32 are provided for ejecting the deep-drawn container. The stripping plate 32 surrounds the respective molding tool 30 and has an annular projection 33 a, b, c with which the edge of the deep-drawn cup is gripped. When the deep-drawn container is ejected, both the bottom ejector 31 and the scraper plate 32 are moved upwards. This is preferably done synchronously. If - as shown in Fig. 3b - only a bottom ejector 31 is provided, this leads to damage to the lower conical wall section 6 and some steps 8 d to 8 f, because due to the strong undercut the upper steps 8 a, 8 b held in the tool.

In FIG. 4, drawn in the Fig. 3a detail X is shown enlarged. The essentially horizontal wall sections 38 of the molding tool 30 have an inclination angle ε of 3 ° and extend outward into the lower boundary wall 41 of the air suction slots 39 a to 39 f. The width of the slots 39 d to 39 f is approximately equal to twice the wall thickness of the deep-drawn container 1 . By applying a negative pressure to the Luftabsaugschlitze 39 d f to 39 and the application of an excess pressure inside the container 1 presses the material of the container 1 into the slots 39 d, 39 f, so that the sharp edges 14 at the lower end of the can train each level unhindered.

In FIG. 5, drawn in the Fig. 3a detail Y is shown enlarged. The air extraction slots 39 a to 39 f are not shown. The annular projection 31 a of the scraper plate 32 is adapted to the shape of the upper conical wall portion 35 of the mold 30 , so that there is a continuous round transition in the upper region when the scraper plate 32 is at rest. The annular projection 33 a engages under the opening edge 5 of the deep-drawn container 1 and detects it when the scraper plate 32 is moved upward in the direction of the arrow. Due to the interaction with the bottom ejector, which cannot be seen in FIG. 5, the deep-drawn container 1 is both pulled out by the stripper plate 32 and pushed out by the bottom ejector. The forces acting on the container 1 are thus evenly distributed.

Reference list

1 container
2nd container
3rd Peripheral wall
4th Opening edge
6 lower conical wall section
7 upper conical wall section
8tha- f levels
9 Step section
10tha, b, c, d counter-conical wall section
11 Tank bottom
12th Transition section
14 Edge
15 slot
16 Plateau section
18th horizontal
20tha, b, c, d counter-conical wall section
30th Molding tool
31 Floor ejector
32 Scraper plate
33a, b, c annular projection
34 lower conical wall section
35 upper conical wall section
36a- f levels
37 counter-conical wall section
38 horizontal wall section
39a- f slot
40 lower boundary wall

Claims (17)

1. Stackable, thin-walled container, in particular a drinking cup made of plastic that can be used in automatic beverage dispensers, the peripheral wall of which widens at least in one area at an angle α in a plurality of successive steps, each step having a counter-conical wall section which is formed in the lower edge a support shoulder in the interior of the container merges into a transition section, characterized in that
that the conical angle γ of the conical wall section ( 10 ) is more than 3 ° and
that the transition section ( 12 ) adjoins the counter-conical wall section ( 10 a, b, c, d, 20 a, b, c, d), forming a sharp, outwardly facing edge ( 14 ). 2. Container according to claim 1, characterized in that the Counter taper angle γ is 3-6 °. 3. Container according to claim 1 or 2, characterized in that the transition section ( 12 ) has a flat plateau section ( 16 ). 4. Container according to one of claims 1 to 3, characterized in that the plateau section ( 16 ) is inclined by an angle β 0 with respect to the horizontal ( 18 ), so that the plateau section ( 16 ) rises inwards. 5. A container according to claim 4, characterized in that the angle β Is 0 ° -3 °. 6. Container according to one of claims 1 to 5, characterized in that all plateau sections ( 16 ) with the exception of the upper plateau section ( 16 ) of the inner cup ( 1 ) rest on the plateau sections ( 16 ) of the outer cup ( 2 ). 7. A container according to claim 6, characterized in that the support area A of the plateau sections ( 16 ) is at least one third of the width B of the plateau sections ( 16 ). 8. Container according to one of claims 1 to 7, characterized in that the weight of a 0.2 l container ( 1 , 2 ) is less than 3 g. 9. Container according to one of claims 1 to 8, characterized in that the angle α is between 7 and 11 °. 10. Process for the production of stackable, thin-walled containers, drinking cups that can be used in particular in vending machines for drinks made of plastic, the peripheral wall of which is at least in one area at an angle α in a plurality of successive Steps extended upwards, with each step a counter-conical Has wall section, the formation of a in the lower edge Support shoulder inside the container in a transition section passes in which an extruded plastic film into a mold deep-drawn by applying a vacuum, the deep-drawn Then punched out the container and then out of the mold is ejected characterized,  that an overpressure and a additional negative pressure in the area of the lower edge of the counter-conical wall section of each step is created. 11. The method according to claim 10, characterized in that the additional negative pressure 0.5 to 1 bar and the excess pressure 4 to 8 bar is. 12. The method according to claim 10 or 11, characterized in that after deep drawing the deep drawn container for ejection from the Forming tool is detected on its edge and on its bottom. 13. Forming tool for the production of stackable, thin-walled containers, in particular plastic drinking cups that can be used in automatic beverage dispensers, the peripheral wall of which widens at least in a region at an angle ϑ in a plurality of successive steps, each step having a counter-conical wall section and an essentially horizontal one Wall section, air suction openings being provided in the lower region of the counter-conical wall sections, characterized in that
that the conical angle δ of the conical wall section ( 37 ) is more than 3 °,
that the horizontal wall section ( 38 ) is inclined by an angle ε 0 and
that the air extraction openings are circumferential slots ( 39 a-f). 14. Molding tool according to claim 13, characterized in that the Counter taper angle δ 3 ° -6 ° and the angle ε 0 ° -3 °.   15. Molding tool according to claim 13 or 14, characterized in that the horizontal wall section ( 38 ) continues outwards in the lower boundary wall ( 40 ) of the slot ( 39 a-f). 16. Forming tool according to one of claims 13 to 15, characterized in that the width of the slots ( 39 a-f) is equal to 2 to 5 times the wall thickness of the deep-drawn container ( 1 , 2 ). 17. Molding tool according to one of claims 13 to 16, characterized in that the molding tool ( 30 ) is surrounded by a scraper plate ( 32 ) for ejecting the deep-drawn container ( 1 , 2 ), which has an annular projection ( 33 a, b, c ) for reaching under the container rim ( 4 ).