DE2717298A1 - COMPOSITE LID AND METHOD OF ITS MANUFACTURING - Google Patents

Description

TlEDTKE - BüHL.NG "K.NNE - GrUPE ££

Dipl.-Ing. Kinne Dipl.-Ing. Group

Bavarlarlng 4, P.O. Box 20 2403 8000 Munich 2

Tel .: (0 89) 53 96 53-56

Telex: 5 24 845 tipat

cable. Germaniapatent Munich

April 19, 1977

B 8123 / ICI case Po 28722

Imperial Chemical Industries

Limited
London / Great Britain

Composite lid
and its method of manufacture

709845/0830

Dresdner Bank (Munich) Account 3939 644 Postscheck (Munich) Account 670-43-804

description

The invention relates to composite lid of the type that consists of a plate made of a first material and Consist of tape, which is molded or cast from a second material around the circumference of the plate. The invention also relates to a method of making a composite lid.

Composite lids of this type are suitable for closing cardboard boxes, as they are for packaging a wide variety of Selling of offered materials or objects, e.g. used food such as ice cream or objects such as hail will. A composite structure enables an edge design made from a flexible thermoplastic material such as polyethylene can be poured precisely, so that a clean fit around the opening edge of the box is ensured in a known manner, while at the same time an area over the area of the lid that can be printed without difficulty is available, so that simple application of a decoration for addressing customers is possible. The first material that makes up the plate is usually cardboard, but a wide variety of laminates can be used in the same way for this purpose. The second material intended for shaping the edge, which also forms the paperboard is usually polyethylene, but many other injection-molded thermoplastic materials can be used.

The composite lids are manufactured in such a way that the plates are cut to the desired OmriB and stacks in a magazine. The panels are usually flat, although they have tabs along the perimeter can that at any stage during the casting process are bent up at right angles} the decorations are

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attached comfortably before stacking. The panels are then led to an injection molding machine in which the edge is cast or molded around the circumference of the plate by injection molding is molded. In order to reduce the required amount of material to a minimum and a well-sealing closure for the carton or box, the lids are made bendable thin; in doing so, however, have got through the discarding of the composite lid results in problems because the molded edges bulge out of the predetermined plane had.

The object of the invention is to create a composite cover of the type described at the outset, in which the edge arching is avoided. It is also an object of the invention to provide a method for producing such a cover to accomplish.

This object is achieved with regard to the cover that in a composite cover with a plate of a first material and an edge cast around the circumference of the plate made of a second material, the plate with preformed Lines of weakness is provided so that the plate warps along predetermined lines and thereby Can relieve tension in the lid, which are caused by the shrinkage of the cast edge. By relieving this Stresses in this way, the aforementioned distortion can be reduced and even eliminated entirely.

The object of the invention is with regard to the method in which a plate made of a first material cuts to a desired outline and casts a rim around the periphery of the plate of a second material, solved by providing the plate with lines of weakness which lie so that the plate is along predetermined Lines can bend or bulge and thereby exist in the lid and due to the shrinkage of the cast-on edge can relieve stress.

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The lines of weakness can go through the most varied known measures can be produced, for example by notching the plate by cutting or scoring, i.e. along it such lines of weakness reduce the cross-sectional thickness of the plate. Alternatively, a compressible plate can be used be compressed along the points where the lines should lie. Unless it is the magazine and the associated Allow mold conveyors, the plate can be embossed to form lines of weakness. Unless the Plate itself has been produced by a casting process, the lines of weakness can be seen as areas of thinner material be shaped. A preferred method is to provide the web with lines of weakness before the Edge is cast around its perimeter; It is useful to provide the lines of weakness when you open the plate cuts to the desired outline.

The most varied arrangements of weakening lines can be selected. With a preferred one Lid is provided at least one line of weakness that runs between two adjacent lid corners and one Path follows which diverges when leaving a corner of the section of the molded edge connecting the two corners and converges to this edge when approaching the other corner. The course of the line can have several straight sections include, wherein there is a sharp bend between adjacent straight sections; the barrel can also change the shape have a smooth curve going from one corner to the other; Finally, it is also a combination of straight and curved Sections possible. The lines between each pair of corners may intersect, but will it is generally preferred to leave an interior area spaced from all corners free of any Lines of weakness is. This gives a relatively flat area with a gentle downward curvature towards the corners; one restricts the weakening lines to the areas around the

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Scope, you can achieve an advantageous design in which all areas of the plate after the stress reduction serving bend lie along the weakening lines within the volume enclosed by the cast-on edge. This allows the lids to be handled on conventional machines, in which they are taken from the stack and then on the filled boxes are placed; these machines cannot in all cases handle lids with the panel section bulging past the top of the rim, i.e. when the plate protrudes over the outside of the volume enclosed by the edge.

The lids can be used for closing molded or molded containers in a conventional manner have a bottom and side walls. But they can also be used in the same way at the two ends of a tube Cross-section can be used so that they form both the bottom and the lid.

The invention is illustrated in the following with the aid of a schematic Drawings of four exemplary embodiments explained in more detail.

Figures 1 and 2 are top plan views of square lids of similar configuration;

Figures 3 and 4 are sectional views taken along the lines III-III and IV-IV in Figures 1 and 2;

Fig. 5 is a plan view of another square lid;

6 is a sectional view taken along line VI-VI in FIG Fig. 5;

Fig. 7 is a top plan view of a triangular lid;

_{Fig. 8 is a sectional view taken} along the line VIII-VIII in Fig. ^{7 709845/0830}

B 8123 -8-

The composite cover according to FIGS. 1 and 3 has a substantially square plate 1 made of a first material, e.g. cardboard and a rim 2 molded around the periphery of the plate from a second material, e.g. polyethylene or is cast on. The edge has a U-shaped or channel cross-section, the legs of which have different heights compared to the Have base 3. The outer leg 4 extends farthest un has a molded locking tongue 5. The inner, shorter leg 6 has a flange 7 protruding at right angles, which is directed away from the outer leg. The four corners 8, 9, 10, 11 are rounded. The plate has correspondingly rounded corners and upwardly bent tabs 12 along each edge. Between adjacent corners, i.e. between corners 8 and 9, 9 and 10, 10 and 11 and 11 and 8 run weakening lines 13, each consisting of two straight sections, which create a hit sharp curtsey 14. Each line diverges when it leaves its corner from the section connecting the two corners of the molded edge 2 and converges to the edge when approaching the other corner. The plate is along the lines 13 are bent so that the concave or plate-like profile shown in FIG. 3 is obtained.

A composite lid according to FIGS. 1 and 3 is produced by the fact that plates that have a square outline with rounded corners and edge flaps 12 are cut, stacks and printed on one side with a pattern. When the outline is cut to size, the printed side is notched in order to obtain lines of weakness 13. Which are still in Plates that are flat or in the flat state are fed to a mold in which the edge is injection molded around the plate is formed, the edge flaps are bent open as shown in the drawings. When removing the plate automatically bulges out of the shape along the lines of weakness to relieve the tension that is in of the plate due to the contraction of the edge during cooling.

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The cover shown in Figs. 2 and 4 is essentially the same as that in Figs. 1 and 3 (for each other corresponding parts have been given the same reference numerals), with the exception that the lines of weakness 21 are soft curves instead of straight legs. In both lids, an inner area 22 is provided, which is spaced apart at all corners, which is free of any lines of weakness. This results in a relatively flat area with a gentle downward movement towards the Curvature towards the corners. As can be seen from Figures 3 and 4, this results in all areas of the plate within of the volume, which is enclosed by the molded edge, the upper and lower edges 23 and 24 point to one or the other side of the plate during these cuts.

Figs. 5 and 6 show a lid which is similar to the preceding two lids is, with the exception of all Lines of weakness 51 meet in the middle. This causes the plate to bulge in the middle to a greater extent the end. Here it is more likely that an overhang will be obtained over the molded edge, with handling problems can occur with some conventional machines.

In Figs. 7 and 8, a triangular lid is shown, which illustrates how the invention can be used in other than usual square or rectangular shapes Here, too, the same reference numerals have been chosen for parts that correspond to one another.

The invention thus provides a composite lid made of a plate made of a first material such as cardboard and one around the Perimeter of the plate made of a second material such as polyethylene molded or cast lid, the plate being preformed Has lines of weakness so that they bulge out along predetermined lines and through the shrinkage of the cast Lid-related tensions in the lid to reduce the lid curvature can be reduced.

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Claims (9)

B 8123 1. Composite cover made from a plate from a first Matert-äl and an edge formed from a second material along the circumference of the cover, characterized in that that the plate (1) has preformed lines of weakness, so that the plate warps along predetermined lines and thereby relieve stresses caused by the shrinkage of the molded or cast-on edge are. 2. composite lid according to claim 1, characterized in that at least one line of weakness (13) is provided, which runs between two adjacent corners of the lid and follows a path that when leaving a corner of the the portion of the molded edge connecting the two corners diverges and then diverges when approaching the other corner converges to the edge. 3. A composite lid according to claim 1 or 2, characterized in that an inner region located at a distance from all corners the plate is free of any lines of weakness. 4. composite lid according to at least one of the preceding claims 1 to 3, characterized in that according to the for Stress relief occurring warping or bending along the lines of weakness all areas of the plate (1) within the the volume enclosed by the molded edge. 5. composite lid according to at least one of the preceding claims, characterized in that the first material Cardboard is. 6. composite lid according to at least one of the preceding claims, characterized in that the second material Is polyethylene. 709 * 45/083 0 ORlGtNAL INSPECTED / B 8123 7. The method for producing a composite lid according to one or more of the preceding claims, in which one Cut sheet of a first material to the desired shape and around the perimeter of the sheet of one second material pours an edge »characterized in that one provides lines of weakness on the plate, which are so arranged are that the plate can warp along predetermined lines and thereby relieve stresses that are in the Lid caused by the shrinkage of the cast edge. 8. The method according to claim 7, characterized in that the plate before casting the edge around its circumference with provides the lines of weakness. 9. The method according to claim 7 or 8, characterized in that the weakening lines are produced by scoring. 709845/0830