DE10214714A1 - Production of tubs or trays by deep drawing comprises molding sheet in female mold using liquid-filled male mold - Google Patents

Abstract

Production of tubs or trays by deep drawing comprises molding sheet (60) in a female mold (20) using a liquid-filled male mold (70). An Independent claim is included for apparatus for producing tubs or trays from sheet comprising a female mold and a male mold which can be filled with liquid which is preferably heated.

Description

The invention relates to a method and an apparatus for producing shaped bodies according to the preamble of claim 1 or Claim 17 and a use of the device according to the Claims 23 and 24.

Deep drawing, also as thermoforming, stretch forming or thermoforming is the transformation of a thermoplastic film or plate into a three-dimensional structure. The starting product is usually webs as well as cuts from sheet metal or foil and also in plastics technology Plates for the production of large-area molded parts.

In film technology, thermoforming is mostly used to produce Packaging materials such as cups, bowls, inserts or trays are used.

For this purpose, a film fixed in a tenter, for example, is first of all heated on one or both sides with infrared radiators until a plastic one State is reached. There are several for a subsequent deformation Possibilities that can be combined with each other. Usually will Compressed air, negative pressure or vacuum as well as mechanical aids and Molding tools used.

In principle, there is the possibility of forming a shaped body Thermoplastic film or plate to be molded without specifying a to blow concrete shape limitation into free space, taking the shape of the blow part by the outline of the stenter, the air pressure and the Temperature is determined. Usually, however, the shape of the Molding given by tools, one negative and one Positive forming are possible. In the case of negative molding, a blister shape is as negative image incorporated into a mold used as a die. The molding tool is coupled to a lifting cylinder, which opens it closes. The mold is moved upwards by a fixed plate completed. The negative molding is usually easier to manufacture, flat shapes with shallow draw depth. With a greater depth of draw there would be a risk that the material to be deformed would be uneven is pulled, resulting in uneven wall thicknesses and thus Weaknesses in the product leads. In these cases, therefore, a preform must be used Compressed air or mechanically using a pre-stretching stamp. This is disadvantageous in two respects, because on the one hand it cools down during the Pre-stretching the material to be deep-drawn - especially with one Compressed air - and preforming also requires an additional one Work step that is particularly in the case of mass products, such as Yogurt cups or similar product packaging is a crucial one Time factor is the production and thus the efficiency of this Manufacturing process deteriorated.

In positive forming, the tool consists of an upper punch, one upper frame and a lower frame. The upper stamp is as positive image of the blister shape. The upper stamp and the lower one Frames are each for opening and closing the tool on one Coupled lifting cylinder. The positive formation is particularly in the case of complex shapes with medium and large drawing depth used. The same applies here: the greater the depth of the draw, the sooner preforming is required. This takes place in the case of positive molding by blowing in compressed air direction on the upper die side and by applying a vacuum on the frame side. The actual shaping takes place in that an upper stamp side Vacuum is applied. This is particularly problematic because First preform compressed air in the direction of the material to be deformed is blown, but spontaneously to form the molded part Vacuum, especially vacuum, must be switched. Furthermore cools the deep-drawn material even during positive molding the preforming, especially with a compressed air insert, so that the Production of shaped bodies with high to very high drawing depths or complex shapes is not possible or only with great effort.

Another variant is for simple components with a small depth of draw also a purely mechanical shaping by means of one serving as a die Frame and a stamp serving as a patrix. This procedure is in particular also for objects made of metal, in particular sheet metal, suitable. Medium and large drawing depths cannot be done in this way or difficult to achieve, because depending on the particular forming inhomogeneities, especially with regard to the Material thickness of the material to be deep-drawn are to be feared, so that Vulnerabilities in the finished product would occur. Undercut shapes are not to be manufactured in this way.

It is common to all these deep-drawing processes that initially one out of one Frame and a cover element existing form is opened. The Deep-drawing material is placed between the frame and the cover element introduced and clamped on the edge. Then there is heating up, for example by means of IR radiation or warm air. When you reach one The actual deep-drawing process then takes place at the predetermined temperature Shaping, which may include preforming, as mentioned above, is connected upstream.

Because the actual shaping only after heating the to deforming material takes place, or because during the actual molding process the material to be deformed is already cooling again, the material must first be heated up very strongly. This means at a high energy expenditure and on the other hand deep drawing such materials are limited to such a high one Minimum deformability temperature far beyond a temperature Withstand adverse effects on their physical and chemical properties. The latter also plays a role in terms of recyclability, for example manufactured products a role, because too much heating a Embrittlement of the starting material is to be feared.

Finally, at such a high temperature, outgassing is To fear plastic components, so that the production, respectively Shaping, immediately downstream filling, in particular Food packaging, with food out of the question since contamination of the food would be feared.

The object of the invention is accordingly a deep-drawing device and a Process for producing shaped bodies in such a way that the aforementioned disadvantages are avoided and a method for It is provided that the formation of complex bodies with a high drawing depth guaranteed under tolerable process conditions, so that immediately the shaping a further processing, in particular a filling, the deep-drawn molded body can be made.

This object is achieved by a method according to claim 1 or by a device according to claim 17 and by uses solved according to claims 23 and 24.

In particular, the object is achieved by a method for producing shaped bodies, in particular hollow bodies, solved by deep drawing, wherein a deformable material forming the body by means of a Liquid which acts as a male, hereinafter referred to as male liquid, is adapted to a die shape.

The main benefit that comes from using one Male fluid results, is that a deformable material, such as. B. a plastic film, due to the pressure of the male liquid can be gently adapted to the shape of the die. Are essential here two factors: on the one hand, a pressure to be applied spreads homogeneously of the entire male fluid and acts evenly on it deforming material. On the other hand, the male liquid does not practice mechanical Frictional forces on the material to be deformed, such as this a stamp would do. Material bruises that are undesirable This would avoid "predetermined breaking points".

In addition, the pressure builds up in the male fluid becomes light and individual to the properties of the starting material can be adjusted. This means that the pressure is maintained even during the Thermoforming process can be varied. When using suitable sensors, the for example the current material thickness of the material to be deformed measure, an immediate pressure adjustment would be possible, for example. The pressure can also be adjusted depending on the die area to be formed to adjust.

According to the invention, deep drawing by means of a male liquid is used Room temperature possible, but it can, according to one embodiment of the Invention can be supported by heating the liquid, provided that Plasticity of the material to be deformed is not at room temperature is sufficient. The temperature of the male fluid can accordingly be adapted to the individual properties of the starting material.

Another major advantage that comes from using a heated Male fluid results in that during the entire Deformation process the same preset temperature of the liquid the material to be treated, namely acts on the material to be deformed. Therefore, a much lower temperature is sufficient for heating of the material to be deformed as if, as with others conventional thermoforming, the material only at the beginning of the process would be warmed. A cooling down during the actual deep drawing process does not take place according to the invention. This affects u. a. positive on a Shrinking of the finished molded parts, as a memory effect with regard to the reached shape at low temperatures more than at high ones Temperatures is pronounced.

According to a further embodiment of the invention, at least one Area of a frame, usually the cover element through which the Liquid enters a male area of the female mold, heated. On this ensures that a potential contact surface of the Frame with the material to be deformed to avoid Temperature differences, tempered to the temperature level of the male liquid is.

It is thus possible to evenly shape the material to be deformed bring the deformation optimal temperature, so that a through the Liquid, preferably via a cover element in the male part is introduced, hydrostatic pressure built up evenly on the entire material to be deformed, which in this way is gentle and is pulled out homogeneously. Even materials with a very low Output strength can be edited in this way.

According to a further embodiment of the invention, at least one Area in which the deformable material, in particular on the edge, is held is, and / or a wall area of the die shape at least on Maintained ambient temperature or especially cooled. That way it is on the one hand possible during the deep drawing process by means of the Male fluid a secure hold of the deformable material in the To ensure stenter, as well as a cooling of the deformable Material immediately upon contact with a wall area of the Effect matrix shape. For example, a small one Peltier elements with heat capacity are used. hereby in particular, complex and / or thick-walled shapes are quickly achieved "fix" and to accelerate the process.

According to a further embodiment, during the deep-drawing process a matrix space on the side facing away from the male fluid Deforming material is vented to ensure a gentle adjustment and applying the material to be deformed to the die shape guarantee. This can be further supported by applying a vacuum become.

According to a further embodiment of the invention, the die space before starting the deep-drawing process with a preferably heated one Tempering fluid at least partially filled. This will be during the Thermoforming process removed from the die space for the aforementioned reasons. Removal can be done either by a simple repression by one progressive shaping of the material to be deformed under the Influence of the male fluid or through an active removal, for example suction.

The use of a tempering fluid has the essential advantage that this extremely simple way of shaping even thicker Starting materials are possible for which one-sided heating is insufficient would. Thermoforming of such thick materials was by conventional methods according to the prior art so far only with great effort or not at all possible.

After the molding has been completed, the male fluid is sucked off or by supplying a gaseous medium from the male part pushed out - a simple pouring is of course also possible - and can then be used again. The male liquid essentially maintains their temperature, so that one for the Heating required for a further molding process is minimized.

If it is a sufficiently flexible molded material, can the resulting shape can be turned inside out. This is the case with thin ones, for example Foils the case, which then directly add a product without additional post-treatment be able to record.

According to one embodiment of the invention, demolding in the Overpressure can be generated. This is for example by blowing in a gas or pressing in a liquid is possible. Demolding can also be carried out mechanically, for example by pushing it out or lifting out.

According to a further embodiment of the invention, between the deformable material and the male fluid at least one, in particular plastic, membrane arranged. In this way, a direct Contact of the liquid treatment medium - the male liquid - with the material to be deformed can be avoided. In this way, a Male liquid, regardless of a potential chemical Incompatibility with the material to be deformed. This is of particular interest if the material to be deformed is high Temperatures of the male liquid at which water is required Male fluid excretes. In such cases, for example, oil or another organic or inorganic liquid become. Mixtures of liquids are also known as male liquid, for example as an oil-water emulsion. However, it should be emphasized that Water is a preferred male medium.

The aforementioned plastic membrane can either permanently with the deforming material to be deformed and after a completed Form stick to this, or it can become rubbery in their Revert to the original undeformed starting position.

According to a further embodiment, the membrane has at least one Through opening through which a filling area is accessible, the between the membrane and another membrane and / or the deformable material is arranged.

For some applications this can be combined with a filling device a product directly in the resulting deep-drawing mold be packed. In such a filling process the corresponding one The deep-drawing mold becomes the one previously required for pressure build-up. Male fluid displaced from the male area, so that the now filled moldings can be taken directly from the mold.

It is also possible according to the invention to use one directly as the male liquid Use liquid to deep-draw the deformable material. After a completed shaping, this remains in the deep-drawing mold, the in turn can only be locked. Come as useful liquid for example, ready-made soups, juices or similar liquid substances Consideration.

Due to the low temperature when using a Male liquid is possible in contrast to the deep-drawing processes previously used is, there is no risk that plastic components from the escaping deforming material, especially degassing. If desired is, of course, as a membrane between the Useful male liquid and the plastic material to be deformed an inert material, in the case of a soup, for example, a metal foil can be introduced.

According to a further embodiment, one that acts as a male Useful liquid between two adjacent and against each other sealed deformable materials, especially foils or sheets, introduced, a simultaneous molding of the two materials if necessary in opposite directions, for example as top and Lower mold, is carried out.

According to a further embodiment, contact surfaces are one deformable material and / or a membrane with at least one other Membrane and / or a deformable material by means of a Sealing device, preferably in an edge area, permanently with one another connected. In this way there is a simultaneous formation of two stacked foils possible. sealers ensure a permanent connection between a top and a Bottom film, for example in the form of a connecting seam. So after that Sealing and molding process a filling of the created space an area is excluded from the sealing. Through this The filling material is transported into the gap between the openings. After that this area is also sealed. Preferably during the Sealing a closure device, such as. B. a screw cap, permanent admitted. This enables the filling material to be filled and removed.

Furthermore, the object of the invention is achieved by a device for Manufacture of shaped bodies, in particular hollow bodies by means of Deep drawing solved, where a deformable material by means of a male a die is fitted, the die being one, preferably heated, Liquid (male liquid) is the one provided in a frame Openings can be pressed into and removed from a male part, is preferably suction.

According to one embodiment of the invention, the die has removal and / or Vents through which a fluid enters a die area can be filled and / or removed therefrom.

This is essential since in this way a tempering fluid, in particular a Gas or liquid of a certain temperature, in which Matrix area can be introduced. In addition, during a deep drawing process the air on the side facing away from the male fluid to be deformed Material can escape from the die area or be sucked out of it become. Air ducts are provided for this, unless a porous one Material such as B. aluminum foam, used as material for the die has been. The openings are preferably those for ventilation serve or used for an inflow or outflow of tempering fluid become, of small diameter, so that a disturbance of the die shape facing side of the surface of the molded body does not take place. In order to conceal a potential surface disturbance, such Openings can also be provided in the form of a pattern, which in the finished Molding is pronounced.

Furthermore, according to a further embodiment, loading and Ventilation openings in the die area to be provided with flaps that at the latest then be closed and a smooth inner Ensure the die surface as soon as the material to be formed is in contact is imminent during the thermoforming process.

A temperature control device ensures according to the invention that the Temperature of the male liquid and / or the fluid and / or the Frame optimally to the properties of the material to be deformed is coordinated. If necessary, the temperature is correspondingly determined by the Temperature control device set or readjusted.

A cooling device for cooling the wall of the die area and / or an area in which the deformable material, in particular edge is held, is also provided. This can either through a tube system built into the die shape or through the Use of a matrix material with high thermal conductivity and one external cooling.

Furthermore, according to one embodiment of the invention Device for attaching a filling device for filling a finished molded hollow body provided. There is also a sealing device and / or a device for attaching a, in particular reclosable Locking device provided.

The object of the invention is further achieved by using a aforementioned device for the simultaneous production and filling of a Solved packaging container, which according to a further embodiment in Connection to it is sealed.

Further embodiments of the invention result from the Dependent claims.

The invention is described below using exemplary embodiments and Figures described in more detail.

Here show:

Fig. 1 is a schematic representation of the first embodiment of the invention;

Fig. 2 shows a second embodiment of the invention, in which the use of a membrane is shown schematically;

Fig. 3 shows a further embodiment of the invention illustrating the use of a Temperflüssigkeit;

Fig. 4 shows an embodiment of the invention, which illustrates the use of an undercut die shape and

Fig. 5 shows an embodiment of the invention, in which a filling of a molded body is shown.

In the following description, the same and equivalent Parts used the same reference numbers.

Fig. 1 is divided into three sub-figures with the designations 1 A, 1 B and 1 C, which schematically show the formation of a hollow body by deep drawing using the method according to the invention.

Fig. 1 thus shows a clamping frame 10 of a die 20 and a lid member 40 having openings for a Patrizenflüssigkeit 50 consists. A film 60 is arranged above the cover element 40 and is held in an edge-side holding area 80 between the cover element 40 and the die 20 . The arrows 90 , which are not described in more detail below, symbolize the entry of a male liquid into a male area 70 , so that the film 60 bulges into the male area 30 . During bulging, gas located in the die area 30 exits through openings (not shown) in the die 20 , so that the film 60 can be deposited homogeneously and uniformly on the inner die wall.

Fig. 2 is also divided into three sub-figures 2A, 2B and 2C analogous to Fig. 1. In essence, Fig. 2 shows the same thermoforming process as shown in FIG. 1. However, it is disposed between the air flowing in through the openings 50 Patrizenflüssigkeit a membrane 100 between the film 60 and the Patrizenflüssigkeit, respectively the Patrizenbereich 70th The membrane 100 is held together with the film 60 in an edge-side holding area 80 between the die 20 and the cover element 40 and is formed with the film 60 during the deep-drawing process.

Fig. 3 also includes three sub-figures 3 A, 3 B and 3 C, which in this order the sequence of a deep-drawing process according to the invention using a tempered male fluid and an annealing fluid, which is passed through openings 120 on the top of the die 20 in a die area 30 , represent.

The direction of flow of the tempering fluid is symbolized by arrow 110 in FIG. 3A. In this way, it is possible to deep-form a thick film 60 , which is held in an edge-side holding area 80 of the frame 10 between a cover element 40 and a die 20 . Fig. 3B illustrates how reaches the extent to which Patrizenflüssigkeit through openings 50 in the Patrizenbereich 70, 110 Temperfluid flows from the openings 120 in accordance with the arrows from the die area 30, shown to the film 60 as shown in Fig. 3C, lies completely against the inner wall of the die 20 . The openings 120 , through which the tempering fluid flows out, are now closed in the region of the inner wall of the die 20 with flaps (not shown), so that the film 60 lies homogeneously and uniformly on the inner wall of the die 20 .

Fig. 4 shows a schematic device according to the invention with an undercut material shape. The method according to the invention for producing a molded body is also suitable for producing a deep-drawing mold with an undercut. Since the liquid used expands evenly on all sides, the same pressure prevails at every point of the male liquid and thus also of the film. When using a suitable material to be treated, it is possible to implement every conceivable shape for a hollow mold. Matrices, in which a division is provided for the removal of the material to be treated, also make it possible to produce complicated, rigid forms which would not withstand any strain from deformation. This is provided according to the invention. The process variants already presented can also be used for these forms.

FIG. 5 shows a variant of the method according to the invention, in which a filling device 130 through a membrane 100 creates the possibility of transporting a useful liquid into a receiving area 140 for the useful liquid. By introducing the useful liquid, the male fluid is displaced from the male region 70 in an opposite manner. The receiving area 140 can be filled immediately after the film 60 has been shaped. The membrane 100 is designed to be plastically, rubber-like and flexible so that when the receiving area 140 is filled, it gradually reverts to its starting position below the cover element 40 . The film 60 is shaped analogously to the methods already mentioned above.

At this point, it should be pointed out that all the parts described above are seen on their own and in any combination, in particular the details shown in the drawings, are claimed as essential to the invention. Modifications thereof, in particular combinations with the aforementioned prior art, are familiar to the person skilled in the art. Legend: 10 frames
20 die
30 die area
40 cover element
50 openings for male liquid
60 foil
70 male area
80 edge-side holding area
90 arrows for the direction of movement of the male fluid
100 membrane
110 arrows for the direction of movement of the tempering fluid
120 opening for tempering fluid
130 filling device
140 receiving area for useful liquid

Claims (24)

1. A method for producing shaped bodies, in particular hollow bodies, by means of deep drawing, characterized in that a deformable material forming the body is adapted to a die shape by means of a liquid acting as a male part (male liquid). 2. The method according to claim 1, characterized in that the deep-drawing process by heating the male fluid is supported. 3. The method according to claim 2, characterized in that the male liquid is heated to a temperature below of the temperature which is the case during a deep-drawing process State of the art is required. 4. The method according to any one of the preceding claims, characterized in that at least a portion of a frame through which the male fluid enters a male region of the female mold, is heated. 5. The method according to any one of the preceding claims, characterized in that at least one area in which the deformable material, in particular edge, is held, and / or a wall area of the Die shape kept at least at ambient temperature, especially cooled. 6. The method according to any one of the preceding claims, characterized in that a die space during the deep-drawing process, in particular through Applying a vacuum, is vented. 7. The method according to claim 6, characterized in that the die space before starting the thermoforming process with a preferably heated tempering fluid is at least partially filled, that is removed from the die space during the deep-drawing process becomes. 8. The method according to any one of the preceding claims, characterized in that to demold the male fluid from the male area removed, in particular suctioned off, and / or a vacuum applied becomes. 9. The method according to any one of the preceding claims, characterized in that an excess pressure is generated in the die space for demolding. 10. The method according to any one of the preceding claims, characterized in that between the deformable material and the male fluid at least one, in particular plastic, membrane is arranged. 11. The method according to claim 10, characterized in that a membrane has at least one through opening through which a filling area is accessible between the membrane and a another membrane and / or the deformable material is arranged. 12. The method according to any one of claims 10 or 11, characterized in that the filling area after the deep-drawing process with a useful liquid is filled. 13. The method according to claim 12, characterized in that the useful liquid as a male liquid for deep drawing of the deformable material. 14. The method according to any one of the preceding claims, characterized in that a useful liquid acting as a male between two adjacent arranged and mutually sealed deformable materials, in particular foils or sheets is introduced, with a simultaneous molding of the two materials is carried out. 15. The method according to any one of the preceding claims, characterized in that Contact surfaces of a deformable material and / or membrane with at least one other membrane and / or deformable material be permanently connected by means of a sealing device. 16. The method according to claim 15, characterized in that a filling area, in particular with a closure device, in a seal-free area is formed. 17. Device for producing shaped bodies, in particular Hollow bodies, by means of deep drawing, whereby a deformable material is adapted to a matrix by means of a male part, characterized in that the male part is a, preferably heated, liquid (Male liquid), which through openings provided in a frame in a male part can be pressed in and removed, preferably is suction. 18. The apparatus according to claim 17, characterized in that the die has ventilation and / or ventilation openings through which a Fluid can be filled into and / or removed from a die area is. 19. Device according to one of claims 17 or 18, characterized in that at least one temperature control device for setting the Temperature of the male liquid and / or the fluid and / or the Framework is provided. 20. Device according to one of claims 17 to 19, characterized in that at least one cooling device for cooling the wall of the Matrix area and / or an area in which the deformable Material, in particular on the edge side, is provided. 21. Device according to one of claims 17 to 20, characterized in that a filling device for filling the shaped hollow body is provided. 22. The device according to one of claims 17 to 21, characterized in that a sealing device and / or a device for attaching a in particular resealable closure device is provided is. 23. Use of a device according to one of claims 17 to 22 for the simultaneous production and filling of a packaging container. 24. Use of a device according to one of claims 17 to 22 for the simultaneous production, filling and sealing of a Packaging container.