DE1479680A1 - One-piece container with exactly parallel vertical walls as well as the method and device for its production - Google Patents

Description

DIPL. ING. G. PULSE I ^ "» »-, ^. ^ , SCHWEIÖEHSTHA8SE S DR.KVPBCHMANN I ", ^ ₄ ™ I tklkfon 88 Οβ 81 i479680 PATENT LAWYERS

1-28 696

Friction to the patent application

SHELL INTERNATIONAL RESEARCH MAATSOHAPPIJ N.V.,

Hague, Netherlands

concerning

One-piece container with exactly parallel vertical walls as well as the method and device for its manufacture.

The invention relates to ^v experience and devices for the manufacture of one-piece containers with exactly parallel vertical walls.

In the manufacture of such one-piece containers, it has hitherto been customary to provide the containers with upwardly and outwardly diverging side and end walls. One reason for using such a container construction may be that it is possible with such containers A more important reason for the use of such a container construction, however, is the need to provide the mold used in the manufacture of the containers with a so-called suit; in other words, it is necessary to have upwardly diverging walls to be provided so that the finished container ^{can be stripped from the ± l} orm after the manufacturing process is completed.

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If one-piece containers are to be designed so that they can be stacked on top of one another, it is now necessary to modify one or more of the container walls in a suitable manner because of the presence of the upwardly diverging walls described, for example by making these walls perpendicular extending curved parts or stacking columns, each of which extends inwardly from the upper part of the container. This fact has led to various complicated container constructions being proposed; All of these constructions can only be produced at high costs, and in particular there is a high expenditure for the provision of the required tools.

A significant disadvantage that has so far arisen in the manufacture of containers is that, if Similar containers are to be produced that differ only in terms of their vertical height is one for each container size having a certain height to provide a separate set of tools. The manufacturers of such containers therefore had to have numerous different ones Keep tool sets ready, even though only one such tool set was used at any given time or one used only a small number of such tool kits. At the same time, there are high operating costs because of the high costs for the Procurement of the various tool sets, the costs for the storage of unused tool sets as well as the time required, which is due to the fact that the Y / tool kit used must always be replaced when the container with a other height are to be produced.

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In the manufacture of containers that can be stacked on top of one another, it has hitherto been necessary to ensure compliance with close mechanical tolerances in those parts of the containers that work together when the containers are stacked on top of one another. Some shaping methods that would be suitable in other thermoplastic materials for processing, for example, can be in the creation of stackable containers do not apply because it nioht learn ^v these is possible to meet the erforderllohen tight mechanical tolerances "

It is often desirable to provide the containers made in one piece with aligned, paired, vertical grooves on the inside of the walls, so that Removable vertical partition walls can be inserted into two mutually assigned grooves · Because of the presence of such grooves on the inside of the wall surfaces of the However, until now it is possible for containers with diverging walls to provide stacking means, all of which Meet requirements

An object of the invention is now to f procedures and to provide devices which make it possible to manufacture one-piece sawn i containers that have exactly parallel vertical walls, and in which it nioht orforderlich is, to guarantee the stackability column parts or other form elements on the To provide inside of the walls, and wherein the disadvantages mentioned above are avoided.

For this purpose, the method according to the invention comprises measures to heat a piece of flat material in order to make it deformable

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to make further around the piece of flat material to the core part of a mold hang up, exactly parallel outer walls has, so that by applying pressure to the bottom as well as the ^east eiten- and end walls a one-part container can be formed to continue the material in a controlled manner so to cool so that the upper part of the side and end walls of the container

cool more slowly than the lower parts of the container, and then, when the hardening of the material is partially complete, However, while the upper parts of the side and end walls are still in a somewhat expanded state compared to their lower parts, the container produced by the Stripping off the mold core.

The device according to the invention comprises a mandrel with exactly parallel outer side and end wall surfaces, and this Molding core has a calibrated circumferential extension Forming ring for forming the upper edge of the container) furthermore, the device comprises means to bring about an optional cooling of the container to be produced on the mold core in such a way that the with With the help of the molding ring, the part of the container to be formed is cooled more slowly than the lower parts of the container

Her invention will be referred to below with reference to sohematlecher Drawings explained in more detail on an execution example.

* ° Fig. 1 shows in perspective an arrangement according to the invention

^ nung'with a mold core and a mold container, between which α »a piece of flat material made of a thermoplastic material ~ * is sorted from which a container is to be set.

** _p Fig. 2 shows the arrangement in a partially sectioned side view at the beginning of the molding process.

ORIGINAL INSPECTED

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Pig. 3 is a vertical section through the arrangement according to FIG Pig. 1, but shows a later stage of the opening process

Figure 4 is a vertical section taken along line 4-4

in-Fig. 3.

FIG. 5 is a partial horizontal section along line 5-5 in FIG. 3.

Fig. 6 shows, in partial detail, details of the construction of the mandrel.

Fig. 7 shows in perspective, in the reverse position, part of the mold ring for the mold core.

Figure 8 is a fragmentary perspective view of an upper corner of a finished container.

According to FIG. 1, a flat piece of material 10, which consists of a moldable material, for example polyolefin, and has certain dimensions, is firmly clamped at its edges with the aid of a holder 20. A mold or die 30 is disposed below the flat piece of material, while a mandrel or punch "40 disposed above the i'lachmaterialstücks. Before the piece of flat material is arranged in the manner shown in Fig. 1 manner, a preliminary step is carried out, which consists in that the piece of flat material is heated at a separate heating station until it sags} immediately thereafter, the piece of flat material is brought into the position shown in FIG. 1 between the two mold or die parts with the aid of the holder 20.

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The deformation of the material is initially only possible with the help of

; ι

the outer die 30 causes the outer die to be subjected to a negative pressure for this purpose. In order to carry out this working step, the piece of flat material 10 and the outer die 30 are moved towards one another in such a way that the upper hand of the outer die engages the underside of the piece of flat material 10 with a sealing effect. By pumping out the outer die 30 it is effected that the middle part of the flat material piece 10 assumes the position shown in FIG. very largely to the inner shape of the wall and floor surfaces of the outer die. The outer die 30 and the inner die 40 are then moved perpendicularly towards one another in such a way that they interlock in the manner shown in FIG. As soon as the die parts assume the position shown in FIG. 3, the outer die 30 is no longer evacuated, and a pressure is applied to both Llutrizonteile which causes the thin material according to FIGS and brought into the desired shape.

ψ The side and end walls of the in senkreor · -; he direction extending portion 41 of the inner die or ^ .cs die 40 precisely parallel to each other. An oraring 42 of rectangular shape can be moved vertically with respect to the stamp oil section 41 *> and can be brought into any desired position, as indicated, for example, in FIG desired height of the container to be produced ar ^ upasaen. A ■ bottom part 33 forms the bottom or the lower v / and of the outer die 30, and this bottom can be adjusted vertically,

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so that it can be brought to any desired altitude to adapt the shape or matrix to the vertical height of a certain container to be manufactured »with the help of suitable ones, here niohi The means shown, the floor 33 can be set at any desired height.

The temperature of the piece of flat material 10 is carefully controlled in the usual manner before the piece of flat material is in the outer die 30 is inserted and the outer die becomes more shaped by suitable means, e.g. Heating elements 34 heated, which enclose the side and end walls of the outer die.

An air hose 36 is connected to the outer die 30, which is in communication with the space under the movable floor 33 stands, and the bottom 33 is provided with a plurality of air openings 37 so that the inside of the outer die as required with a Under or over pressure can be applied. The device is automatically controlled with the aid of means not shown here in such a way that the inside of the outer die is subjected to negative pressure after the upper edge of the outer die comes into contact has come to the underside of the flat material piece 10 and has preferably caused a seal at this point ·. According to Fig. 2 is the upper edge of the outer die 30 with a naoh

to the protruding edge section 38 provided above, along it

A shoulder 39 extends circumferentially on the outside

^? With the help of this section 38 of the outer die, the initial i

^ lent Abdiohtunewirkung brought about, and according to the following

- »Explanation, a final ' _t seal will be effected at a later point in time, whereby the shoulder 39 will also be used. ·.

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Per section 41 of the stamp 4-0 has essentially the Shape of a rectangular block. The underside of the shaped ring 42 enclosing the block section 41 has a groove 43, in which, in the position of the die parts according to FIG. 3, the edge section 38 engages with the shoulder 39 of the outer die 30, however, there is no direct contact, but rather the operating part of the piece of flat material 10 clamped between them will.

The height of the mold ring 42 with respect to the block section H 41 of the punch 40 must therefore correspond to the height of the movable floor 33 correspond to the outer die 30; the position of these two parts is chosen so that a container with the desired vertical dimension or Höfee can be produced. The outer die 30 is supported on the upper side of a support 30a, while the punch 40 is suspended from the underside of an upper support structure 40a. The form ring 42 is at the upper support 40a suspended by a plurality of ring supports 44; the block section 41 is supported by several support devices tungen 46 worn; the support devices 44 and 46 are adjustable so that the relative height of the form ring 42 and the block portion 41 can be varied.

The fully formed container shown in FIGS. 3 and 4 has a bottom 11, end walls 12 and side walls 13; who do not

° turned parts 14 of the piece of flat material 10, the outside of the ^ Die parts are lying, will be cut off and removed later.

- ^. According to FIG. 8, the upper edge of the container points to its inner ω side on a horizontal shoulder 15, furthermore a vertical inner flange section 16 extending upwards, an outwardly extending horizontal edge portion 17 and

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finally an outer flange section 18, which is perpendicular to protrudes below. This shape of the outer flange 18 and the outer hand portion 17 is achieved in that the material 10 between the form ring 42 of the punch and the upper edge portion 38 of the outer die is formed under pressure. It can thus be seen that compliance with the mechanical tolerances in the case of the upper Hand section of the container is ensured by the shape of the two die parts, which means that you have several similar - "containers can perfectly stack on top of each other. Regarding the molding process, the method for molding the Jj The upper edge of the container is important as inevitably a final seal is achieved, which takes the place of the above-mentioned preliminary sealing occurs.

When the walls and bottom of the container to be made pressed against the surface of the Kloteabaohnitts 41, there could be a risk of air being trapped between them. For this reason, several outlet openings 41 · in the FIG. 6 shows the areas of the ground, the Side walls and the end walls of the block section distributed. On the side and front walls, where the clota section crooked Carries beads or ridges 49a, the air outlet openings are preferably in the recesses on both sides of the ridges arranged. In this way there is a guarantee that all of the air from the interior of the container via the outlet openings 41a escape into the hollow Klotiabohnitt 41

eo can.

According to Fig. 7, the form ring 42 carries an inner flange 39, the on its inside ait grooves 39a for receiving the

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Strips 49a of the block section are also provided on the outside of projections 39b, by means of which the grooves 16a of the container to be produced are formed. 8, the top of the flange 39 serves to shape the shoulder 15 of the container.

As already mentioned, the piece of flat material 10 is heated in a separate oven before it is placed between the two dies 40 and 30 parts. If a polyolefin material is used, the preheating temperature is around 200 ° C. The outside

The die 30 is heated to a somewhat lower temperature with the aid of the strip-shaped heating elements 34. The block section 41 is kept at a considerably lower temperature, namely between approximately 50 ° and 90 ° O. The temperature used in each case depends on the material used and the size and height of the holder to be produced. The stack 40 is cooled with the help of pipes 47 and 48, which are held one behind the other) and by means of which the waeeer is conducted at a regulated temperature, via the temperature of the block attachment 41 to dta

| Maintain setpoint. The lower the container to be produced, the lower the temperature generally at which the block section is kept; in the case of deeper containers, the temperature of the block section or stamp is set to a higher value.In any case, the stamp is kept as precisely as possible at a constant temperature which is considerably lower than the solidification temperature of the material, so that at the moment in which the shaping of the material with the help of the punch begins, a cooling effect is initiated which causes the material to begin to solidify.

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The outer die 30 is provided with a cooling tube 35 which extends all over the area near the upper ends of the die walls Extends circumference of the outer die. The top of the tube 35 is provided with small openings spaced at intervals. When the molding of the material with the aid of the punch 41 begins, the cooling of the material is initiated; at this ^ wake compressed air is supplied via the pipe 35 and via the openings just above and outside against the underside of the waste material 14 which is therefore cooled down quickly.

The material is also cooled from the inside of the outer die 30 in that air is passed through the openings the bottom plate 33 is fed while the material is pressed against the otempel 41. The outer die 30 is on one ötirnwand 31 is provided with a pressure relief valve 36a, which on a certain pressure of e.g. 2.7 atm is set. Compressed air is supplied to the interior of the outer die 30 via the air hose 36 fed to press the material against the punch 41. The pressure of the compressed air source, which is connected to the hose 36, is considerably higher than the pressure to which the pressure relief valve is applied 36a is set so that at the moment this cone pressure is reached within the outer die is compressed air from the hose 36 at high speed flows into the interior of the outer die via the openings 37 and from this constantly escapes via the pressure relief valve 36a.

Thus, it cools and hardens the material causes compressed air to be introduced into the outer die 30, that the punch 41 is kept at a relatively low temperature before coming into contact with the considerably hotter material

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tion comes, and that the plunger 41 is constantly cooled by the water kept at a controlled temperature, the through the lines 47 and 48 flows. At the same time, the air escaping from the pipe 55 ensures very rapid cooling of the excess material 14.

An important feature of the invention is that the upper rim portion of the container is cooled more slowly than the rest of the container. Three different factors contribute to this slower cooling of the edge section of the Container, firstly the fact that the edge portion of the container has a slightly greater thickness than that Side walls and bottom, secondly the fact that the edge portion of the container is formed by the application of pressure, wherein the material between the two die parts is detected, so that the material in this area has a higher density and thirdly, the fact that the edge portion of the container which is formed by the application of pressure is in is exposed to a lesser degree of the cooling effect of the outer die, i.e. the air flowing through the outer die.

Although the air flowing through the inside of the outer die cools the metal side and end walls of the outer die, whereby a certain cooling effect is exerted on the edge portion of the container, but is The cooling effect of the air flowing inside the outer die on the side and end walls of the container has a more direct effect, so that the cooling occurs much faster.

An important feature of the one used according to the invention Polyolefin material or an equivalent material

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in that the material cools down and hardens .contracts. The slower cooling of the container edge therefore leads to the fact that the upper parts of the side and end walls in remain in a somewhat expanded state, i.e. their dimensions are at least a few hundredths of a millimeter larger are than those of the lower parts of the side and end walls before the hardening of the material is complete. The container will stripped from the die parts before the setting process is complete and while the upper parts of the walls are still in in this somewhat expanded state. -

It is necessary that the form ring 42 engages the block section 41 with a tight fit, specifically at every height position of the form ring with respect to the block section. This naturally requires that the side and end walls of the block section 41 run exactly parallel to one another. Thus, although no suit or no taper is present in the matrix, it is possible to strip the container from the boss portion just before the time at which the hardening process is completed, so that containers of high quality and with high production g tion rate can be produced, which is required in a production according to modern aspects.

Referring to the drawings, the relief valve 36a is the Outer die arranged above the point where the movable floor 33 was attached. In practice, however, it will It is preferred to arrange the pressure relief valve near the bottom of the outer die in such a way that it is always below the bottom 33. The advantage of this arrangement is that any contact between the container material and the inlet channel of the

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Pressure relief valve is avoided, and that therefore does not pose a risk exists that the container is improperly shaped because air is escaping through the pressure relief valve.

The fact that the material is formed by pressing it against the punch 41 results in a further advantage which cannot be easily recognized. This advantage is related to the adjustability of the tool, which enables the production of containers of different heights. When a container of small height is produced, there are quite a number of outlet openings 41a which are located above the mold ring 42; however, it is not necessary to close these unused outlet openings. If it were provided, however, to evacuate the interior of the die 41, should all of the openings are not used, the connection between the inside and the outside are closed manufacture of the punch, and from this, considerable difficulties would bility with respect to the ^v first]] of the tool yield .

The method and the device according to the invention can also be used in the manufacture of straight-walled containers as in the case of the containers described above, the walls of which are provided with strips. An advantage of the container construction, • in which the walls are provided with strips, however, there is daring that you can get by with a smaller amount of material if Containers are to be produced whose strength allows several containers to be stacked on top of one another.

It should be noted that the. Hose section 48 is built into the form ring 42 and can be moved together with the form ring, and that the hose sections 47 and 48 are connected to one another by a flexible intermediate section 47a.

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Claims;

Claims (10)

- 15 - 1A-28 696 PATENT CLAIMS 1.7 A method for forming a one-piece container with exactly parallel vertical walls, characterized in that a piece of flat material is heated in order to make it deformable, that the piece of flat material is brought into contact with an inner die or a punch which has exactly parallel outer walls, so that a one-piece g container be formed by applying pressure to the bottom and the side and end walls, that the material is cooled in a controlled manner so that the upper parts of the side and end walls to cool slowly the -Behälters than the lower container parts, and that when the hardening of the material is partially complete, but while the upper parts of the side and end walls are still in a somewhat expanded state compared to their lower parts, the finished container is stripped from the punch. j 2. The method according to claim 1, characterized marked λ is characterized in that a by applying pressure of extending in the circumferential direction between the edge of the container; Part of the punch and the adjacent part of an outer die ^; is formed, and that inevitably a cooling effect is exerted on the bottom as well as the side and end walls of the container, while at the same time the exertion of such an inevitable cooling effect on the mentioned part of the outer mattress is avoided in order to ensure that the one running in the circumferential direction The edge of the container cools down more slowly compared to the side walls and the bottom of the container. 909828 / 13U - iw -. IA- £ 0 3. The method according to claim 2, characterized in that the edge extending in the circumferential direction 'of the container between the one running in the circumferential direction upper part of an outer die and a molding ring of the punch extending in the circumferential direction is formed »whereby the mentioned XeAl of the outer die is inevitably protected. 4. Device for forming a one-piece container with exactly parallel vertical walls, characterized by an inner die or a punch with exactly parallel outer side and end wall surfaces, the punch a molded ring extending in the circumferential direction Forms of the upper edge of the container running in the circumferential direction, as well as means for optional cooling to effect the container to be formed on the stamp in such a way that the part of the container to be formed with the aid of the foraringe The lower parts of the container cool down more slowly. 5. Device according to claim 4, characterized in that the cooling means comprise suitable means for direct cooling of the aforementioned to effect lower parts of the container, as well as means for indirect cooling of the upper edge portions of the container cause· 6. Apparatus according to claim 4 or 5, characterized in that the shaped ring extending in the circumferential direction is perpendicular to the remaining part of the punch . is adjustable, the molded ring with a tight fit to the attacks vertical walls of the stamp, without consideration on the selected height of the mold ring, and that means are provided 909828 / 13U - 17 - 1A-2Ö 69 are to be seen opposite the Fonnring in the selected altitude the punch or the inner die. 7. Apparatus according to claim 6, characterized in that an outer die is provided which one has vertically movable floor which can be brought into a selected height position, wherein the outer die assigns means are to either evacuate or pressurize the inside of the outer die. 8 · Device according to claim 4 to 7, characterized in that M indicates that the punch is hollow, and that the walls of the punch have outlet openings which create a connection between the inside and the outside of the stamp « Apparatus according to claims 6 to 8, characterized in that the punch is provided with vertical beads or strips distributed at horizontal intervals, which are arranged on the side and end wall surfaces of the punch, and that the inside of the molding ring has ä Grooves are provided in which the associated strips can engage. 10. One-piece container with exactly parallel verticals Walls, gekennzeichne.t by their production with the aid of the method according to claim 1. 909828 / 13U