DE2717298C3 - Method of making a composite lid - Google Patents

Description

The invention relates to a method for producing a composite cover according to the preamble of claim 1.

Composite lids made in this way are suitable for closing cardboard boxes, as they are for the Packing a wide variety of materials or items for sale, e.g. B. Food like Ice cream or objects such as nails can be used. A composite lid enables an edge design, which can be precisely cast from a flexible thermoplastic material such as polyethylene, 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 cover plate that can be printed without difficulty It is available, so that it is possible to simply apply a decoration to address the customer. The material forming the cover plate is usually cardboard, but the most varied of materials can also be used Laminates can be used in the same way for this purpose. The one for shaping the edge The second material envisaged is usually polyethylene, but numerous others can also be used Injection molding processable thermoplastic materials can be used.

The composite lids are manufactured in such a way that the cover plates are made to the desired outline cuts and stacks in a magazine. The top panels are usually flat, even if they are may have tabs along the perimeter that are at any stage during the casting process be bent up at right angles; the decorations are usually attached before stacking the die Lid plates are then fed to an injection molding machine, where the rim is molded around by injection molding the lid edge is cast or molded. To keep the required amount of material to a minimum reduce and get a well-sealing closure for the carton or box, the Cover plates selected to be flexible and thin; in doing so, however, by discarding the composite lid Problems arise because the molded edges had bulged out of the predetermined plane.

The object of the invention is to design the method according to the preamble of claim 1 so that the curvature of the edge is avoided.

This object is achieved by the characterized features of claim 1 it is achieved that the cover plate arches along the weakening lines and thus tensions degrades in the material due to the shrinkage of the cast-on edge; are conditional. By relieving These tensions in this way can make the aforesaid warp diminished and even entirely

be eliminated.

The lines of weakness can go through the most varied known measures can be generated, for example by the fact that the cover plate through Cutting or scoring notches, i.e. the cross-sectional thickness of the cover plate is reduced along such weakening lines. Alternatively, a compressible The cover plate can be compressed along the points where the lines should lie. Unless it is Allow magazine and the associated form conveying devices, the cover plate can be used to form Lines of weakness are marked. Provided that the cover plate itself is produced by a casting process the lines of weakness can be shaped as areas of thinner material. A preferred one The method consists in providing the cover sheet with lines of weakness before the edge is around its perimeter is cast on; It is useful to provide the lines of weakness when you have the Cut the cover plate to the desired shape.

The most varied arrangements of weakening lines can be selected. At a preferred composite ceiling] is provided at least one line of weakness between each two adjacent Ceilings and corners and follows a path that

when leaving a corner of the section of the molded edge connecting the two corners diverges and when approaching the other corner converges to this edge. The course of the line can be several include straight sections, with a sharp bend between adjacent straight sections is located; the barrel can also have the shape of a smooth curve going from one corner to the other; finally, a combination of straight and curved sections is also possible. The one between everyone Lines running through pairs of corners may intersect, but it is generally preferred to leave an inner area at a distance from all corners, which is free of any weakening lines is. This results in a relatively flat area with a gently sloping area towards the corners Curvature; if you limit the weakening lines to the areas around the perimeter, you can create a Achieve advantageous design in which all areas of the cover plate after the stress reduction serving bulge along the weakening lines within the by the cast edge enclosed volume. This allows the composite lids to be handled on conventional machines where they are taken from the stack and then placed on the filled shafts; these Machines cannot handle composite lids in all cases where the cover plate is over the The top of the rim is arched, d. H. if the

Cover plate protrudes above the outside of the volume enclosed by the edge

The composite ceiling! can be used for closing molded or cast containers which have a bottom and side walls in the usual way. But you can also use the same Way to be used at the two ends of a tube of suitable cross-section so that they can be used both in the Form the bottom and also the lid.

The invention is explained in more detail below with the aid of schematic drawings of four exemplary embodiments explained

F i g. 1 and 2 are top plan views of square composite lids of similar configuration;

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

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

F i g. Fig. 6 is a sectional view taken along line VI-VI in Fig. 5;

Fig.7 is a plan view of a triangular one Composite lid;

F i g. 8 is a sectional view taken along line VIII-VIII in FIG. 7th

The composite lid according to FIGS. 1 and 3 has a substantially square cover plate 1 from one first serving as a carrier material, e.g. B. cardboard and an edge 2 that goes around the perimeter of the Cover plate made of a second material, e.g. B. Polyethylene is molded or cast on The edge has Ii- or channel cross-section, the legs of which have different heights compared to the base 3. The outer one Leg 4 extends the furthest and has a molded locking tongue 5. The inner, shorter one Leg 6 has a flange 7 protruding at right angles, which is directed away from the outer leg four corners 8, 9, Iu, 11 are rounded The cover plate has correspondingly rounded corners and upwardly bent tabs 12 along each edge. Between adjacent corners, d. H. between the corners 8 and 9, 9 and 10, 10 and 11 and 11 and 8 Weakening lines 13, each consisting of two straight sections, which create a 14 sharp curtsey. Each line diverges when it leaves its corner from the two corners connecting portion of the molded edge 2 and converges when approaching the other corner to Edge. The cover plate is bent along the line 13, so that one can see in Fig.3 concave or plate-like profile receives

A composite lid according to FIGS. 1 and 3 is produced by having cover plates on a square outline with rounded corners and edge flaps 12 are cut, stacks and with a pattern printed on one side When the outline is cropped, the printed side is notched to obtain lines of weakness 13. the Cover plates that are still in the level or flat state are fed to a casting mold in which around the cover plate the edge is formed by injection molding, the edge tabs according to FIG Representation in the drawings are bent. When removing from the mold, the top plate bulges automatically along the lines of weakness in order to relieve the tension that is in the cover plate has built up the contraction of the rim on cooling

The composite lid shown in Figures 2 and 4 is essentially the same as that in Figs. 1 and 3 (for corresponding parts, the the same reference numerals are chosen), with the exception that the weakening lines 21 instead of soft curves make straight legs. Both composite lids have an inner area that is spaced at all corners 22 is provided, which is free of any lines of weakness. This gives a relatively flat one Area of curvature gently downwards towards the corners. As one can see from FIGS. 3 and 4 sees, this leads to the fact that all areas of the cover plate are within the volume that is through the molded edge is enclosed, the upper and lower edges 23 and 24 in these Show cuts to one or the other side of the cover plate.

Figures 5 and 6 show a composite cover which is similar to the previous two composite covers, with the exception that all lines of weakness 51 meet in the middle. This causes the Cover plate in the middle to a larger extent. Here it is more likely that a supernatant is over the molded edge is obtained, with handling problems with some conventional machines may occur.

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

For this purpose 2 sheets of drawings

Claims (4)

Patent claims: 1. Process for the production of a composite cover, in which one consists of a flat carrier material cuts a cover plate and then along the edge of the cover from a plastic, second material pours an edge, characterized in that the cover plate provided with lines of weakness arranged in a certain direction and the cover plate is below the shrinkage stress of the second hardening material can bulge 2. The method according to claim 1, characterized in that that the lines of weakness before casting the second material on the cover plate attaches. 3. The method according to claim 1 or 2, characterized in that the weakening lines generated by scribing. 4. The method according to claim 1 to 3, characterized in that one with angular cover plates the weakening lines here are curved or arrow-shaped from one corner to an adjacent corner pulls