DE8801950U1 - Device for producing plastic moldings - Google Patents

Description

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01« The invention relates to a device for producing plastic orings according to the preamble of claim 1.

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Plastic film, e.g. polystyrene. Between the two layers of plastic film there is another layer made of an absorbent material, e.g. cellulose. The cellulose layer has hygroscopic properties. This means that juice or blood from packaged meat, for example, which flows through the holes in the hole pattern in one of the two plastic films, is absorbed, which significantly improves the appearance of the product.

The plastic moldings are manufactured in a known device in a production line, whereby the two plastic film webs are pulled off a reel each. The two reels are arranged at a distance from each other so that the plastic films run towards each other up to the forming station. Between the two reels for the plastic films there is another reel which produces parallel cellulose strips, the width of which corresponds approximately to the width of the later mold base and which are guided between the two plastic films. Before they are combined in the forming station, the two

Plastic films are heated. In the foraging process, the layers of plastic film, cellulose layer and the other plastic film lying on top of one another are deformed, e.g. by deep drawing. A number of deformations form a mat in which the deformations are arranged like a matrix. The mat is fed to a separation station, e.g. a punch, in which the moldings are punched out of the mat. In a further step, the punched-out moldings are removed from the now loose mat assembly and stacked, while the complementary material of the mat is disposed of as a waste product.

The moldings produced with such a device have significant disadvantages. Because the cellulose layer is arranged between the two plastic film layers over the entire length of the molding, a secure bond between the two plastic films in the edge area of the molding is not guaranteed. When the moldings are used further, e.g. when unstacking and packaging the meat products, the connecting seam between the two plastic films can burst. The moldings thus become unsightly or unusable. This results in another disadvantage. The blood or meat juice absorbed by the cellulose layer escapes from the burst edge areas, which makes the packaging unsightly on the one hand and un-

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Since the offcuts remaining between the moldings also have a layered structure of plastic film and cellulose layer, it is not possible to reuse the waste.

A further disadvantage of the previously known device is that the forming and separating processes take place in separate device stations. After the forming process, the film material cools down, causing the dimensions of the molded parts to shrink. During the subsequent separating process, irregularities in the contours of the molded parts can occur without an exact alignment process. This is particularly true for flat moldings, where self-centering in the separating station, e.g. a punching press, is not readily possible.

The invention is therefore based on the object of designing a device of the type mentioned at the outset in such a way that the production of moldings is made possible in which the plastic films are firmly connected to one another in the edge area and the moldings are separated from the molding assembly exactly along the desired outlines while reducing the construction effort.

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The invention solves the problem with the help of the characterizing parts of claim 1. Further advantageous embodiments of the invention are the subject of 6 subclaims.

In the device according to the invention, the third winding for feeding the material web made of absorbent material is dispensed with. Instead, a labeling device is arranged between the converging plastic film webs, which brings a number of cellulose cutouts corresponding to the number of moldings contained in the molding assembly from the labeling device to the underside of one of the webs and fastens them there. The arrangement of the cutouts on the plastic film corresponds to the later arrangement of the moldings in the matrix. The dimensions of the cutouts correspond approximately to the dimensions of the bottom surfaces of the later moldings, with lateral tolerances between the outlines of the cutouts and the outlines of the bottom area being provided. During the molding and subsequent separation of the moldings from the matrix assembly, the plastic films are directly connected to one another and additionally welded together in the edge area. The forming and separating process takes place in one and the same station, whereby the separating process already begins when the formed, still warm part is placed between the two mold halves, the embossing and

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the mold cup. This ensures that the molded parts are separated from the molded part exactly along the desired circumferential lines. Even molded parts made of compact foils, the individual layers of which can have different thermal expansion coefficients, have 100% accuracy in their circumferential lines. This creates a molded part that is only made up of three layers in the base area, so that the plastic foils can be tightly connected to one another in the edge area. Cracking of the edge area is thus prevented, so that blood or meat juice can no longer escape in this area.

Another advantage is that the layer of absorbent material can be made thicker to improve its efficiency than with a molding produced using the previously known device, since such a thickening does not affect the edge area. Regardless of the thickness of the intermediate layer, an intimate connection of the plastic films in the edge area is still guaranteed. With the previously known device, a thickening of the intermediate layer results in the disadvantages of serving in the edge area of the molding being increased even further.

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A further advantage of the device according to the invention is that the offcuts, which do not contain any pulp material, can be reused.

In an advantageous embodiment according to claim 2, the automatic labeling device has a boom that is moved from the production line under a magazine arranged next to the production line. The boom has a number of tools for receiving the cutouts that corresponds to the number of cutouts to be applied. The boom can be raised and lowered. When raised, it takes the cutouts from the magazine, is lowered, moved back into the production line, and in the raised state it applies the cutouts to the film web. The boom then moves back under the magazine while the film webs are moved one cycle further, so that there is space again for applying further cutouts to the film web. The use of a labeling device not only has the advantage of more efficient and therefore faster production of the moldings. There are also advantages in terms of the accuracy of the cutouts on the film sheet. This ensures that the cutouts are always made exactly at the points on the film sheet that correspond to the later bases of the molding.

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According to claim 3, the forming and separating device consists of embossings arranged in a matrix and/or mold cups complementary to these, whereby the mold cups have recesses running parallel to the stroke direction of the forming device as guides for cutting tools. The recesses and the cutting tools guided in them reproduce the outlines of the moldings exactly. This ensures that the moldings already formed in the forming device are separated from the molding assembly exactly at the desired circumferential lines while the mold is still closed, without the molding material cooling down between the forming and separating processes.

According to claim 4, the cutting tools consist of strip steel, $ »r having a cutting edge at its free end. The strip steel cutting edges clamp the sanders of the moldings between the strip steel cutting edge and the punching plate and weld them in this position. During the production of polystyrene films, smooth surfaces are formed which enclose a foam layer. During the separation process with the help of the strip steel cutting edges, these draw a smooth outer skin around the foam structures of the two plastic films that are attached to one another and the contact area of the two plastic films and weld this outer skin to the corresponding outer skin of the other plastic film.

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fabric film. The edge area of the molded part is thus securely sealed by the respective outer skins of the plastic films.

Advantageously, according to claim 5, the hole patterns are introduced into one of the films by means of perforated rollers, such that the hole patterns are located exactly at the points in the film that correspond to the base area of the moldings or the position of the cutouts on the film.

In the following, the invention is illustrated and explained in more detail using drawings.

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Fig. 1 schematic side view of the device for producing plastic moldings;

Fig. 2 Device according to Fig. 1 in plan view, whereby the upper plastic sheet and the device locations arranged above the upper plastic sheet have been omitted for reasons of clarity.

In Fig. 1, reference numerals (1 and 2) indicate two windings arranged vertically relative to one another for an upper (3) and a lower (4) plastic oil web

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Si· Plastic film webs (3 and 4) are unwound from the reels (1 and 2) and guided around rollers (β and 6) so that the film webs (3 and 4) run at a parallel distance from one another. As the plastic film webs continue, they are guided around rollers (7 and 8), whereby they are transported further at an angle towards one another. In the processing direction behind the rollers (7 and 8) there is a heating station (9) which is followed by a combined forming and separating station (10). The forming and separating station (10) is followed by a stacking station (11). Between the rollers (5, 6; 7, 8) in the space between the plastic webs (3 and 4) running parallel there is a labeling device (12). The labeling device (12) has a boom (13) which, on its side facing the film web (3), carries tools (14) which take sections (17) of a suitable material, e.g. a layer of cellulose, from a magazine (15) shown in Fig. 2. For this purpose, the boom (13) can be swung out of the processing line, i.e. from the space between the plastic films (3 and 4) under the discharge openings of the magazine (15) about the axis (16). At the same time, the boom (13) can be raised and lowered according to the double arrow (27).

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The plastic films (3 and 4) are transported in cycles through the entire device. During each cycle, i.e. each time the transport device stops, the boom (13) is swung under the plastic film (3). In this position it is raised and during the lifting process transfers the cutouts (17) located on the top of its tools (14) to the bottom of the plastic film (3). They are secured there. Then the boom (13) is lowered again and swings under the output shaft of the magazine (15), where it is raised again and picks up another number of cutouts (17) of the pulp material. When the boom swings back into its working position, the plastic films (3 and 4) continue to move in the direction of the heating station (9). In the station (9), the plastic films (3 and 4) are heated and fed to the forming and separating station (10) in this heated state. The forming and separating station (10) consists of two lifting tables (18 and 19), whereby the upper lifting table (18) has mold cups arranged in a matrix arrangement on its underside and the lower lifting table (19) has embossings on its upper side in a corresponding matrix arrangement. However, the embossings can also be arranged on the upper lifting table and the mold cups on the lower lifting table. In this way, a large number of moldings can be produced during a single cycle. The arrangement of the tools (14) on

The distance between the outrigger (13) corresponds to the arrangement of the mold pockets or embossings in the mold and separating station (10). This ensures that the cellulose cutouts (17) made on the upper plastic film (3) using the tools (14) are each positioned precisely in the area of the plastic film (3) that will form the bottom area of the subsequent molding. The dimensions of the cutouts and the dimensions of the bottom differ to a certain extent. These tolerances are necessary to ensure that the plastic films (3 and 4) are firmly connected in the edge area of the molding in every case.

The heated plastic films (3 and 4) with the pulp cutouts arranged between them are formed into shapes in the mold cups and embossings. While the mold is still closed, the molds are separated from the matrix. This is done, for example, with the help of strip steel cutting edges that are arranged in the shape of the mold outlines. The strip steel cutting edges weld the pressed plastic films (3 and 4) together in the edge area of the mold. In the next cycle, the molds are lifted out of the film laminate in the stacking station and stacked sideways. The film laminate waste can then be reused.

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At each cycle, i.e. when the advance of the foil conveyors (3 and 4) is interrupted, the roller conveyor is simultaneously provided with pulp cuts, the moldings are formed and separated from the matrix structure and the already finished moldings are stacked using the stacking device.

So that the juice or blood from the meat to be packaged later can be absorbed by the pulp cutout, holes are arranged in a regular or irregular pattern on the upper plastic film (3) in the area of the applied pulp cutouts. The hole pattern is introduced into the film (3) by the perforated rollers (28).

Claims (5)

Protection claims 1. Device for producing plastic moldings, e.g. plastic bowls, from two plastic film webs, one of which is provided with hole patterns, with a layer of an absorbent material arranged between the webs, e.g. B. Cellulose, whereby the moldings are formed in cycles from the heated plastic film webs in several at the same time in a matrix during one cycle and separated from the matrix structure, whereby the device essentially consists of a delivery station for the plastic film webs, an adjoining heating station, a forming station and a separating station and a stacking device, characterized in that in the film transport direction behind the delivery station (1, 2) and in front of the heating station (9) between the film webs (3, 4) a labeling device (12) is arranged, and that a combined forming and separating device (10) is arranged adjacent to the heating station (9), to which the stacking device (11) is connected. 2. Device according to claim 1, characterized in that the labeling device (12) has a boom (13) which can be raised and lowered and can be pivoted in a horizontal direction perpendicular to the film movement direction from the area between the two film webs (3, 4) under the discharge openings of a magazine (15) for the cutouts (17) arranged next to the film webs (3, 4). Il «I«* · &diams; 3. Device according to claim 1 or 2, characterized in that the deformation and separation device (10) consists of embossings arranged in a matrix and/or mold cups complementary to these, the mold cups having recesses running parallel to the direction of travel of the molding device as guides for cutting tools. 4. Device according to claim 3, characterized in that the cutting tools consist of strip steel which has a cutting edge at its free end. 5. Device according to one or more of claims 1 to 4, characterized in that perforated rollers (28) for perforating one of the plastic film webs (3) are arranged between the dispensing station (1) and the labeling device (12). I IMI t ti I 4 · I « · I* If· '