DE2717298B2 - 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 manufactured according to this / \ rt are for the closing of boxes, as they are for the Packing a wide variety of materials or objects offered for sale, ζ. Κ food like Ice cream or objects such as nails can be used. A composite lid enables an edge design that consists of a flexible thermoplastic Material like polyethylene can be precisely cast so that a neat fit around the opening edge of the Cardboard boxes are guaranteed in a known manner, while at the same time an area over the area of the cover plate that can be printed without difficulty Is available, so that simple application of a decoration for addressing customers is possible. 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 that the cover plates are cut to the desired shape and stacked in a magazine. the Top panels are usually flat, although they may have tabs around the perimeter that cut into be bent up at right angles at any stage during the casting process; the ornaments are usually attached before stacking. The top panels 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; have yourself 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 enl'.ang the

to warps weakening lines and thereby relieves tension in the material caused by the shrinkage of the molded edge are conditional. By relieving these tensions in this way, the aforementioned distortion can be reduced and even entirely be eliminated.

The weakening lines can be generated by the most varied of known measures, z. B. by notching the cover plate by cutting or scoring, i.e. along such Lines of weakness reduce the cross-sectional thickness of the cover plate. Alternatively, a! Compressible The cover plate can be compressed along the points where the lines should lie. Unless it is Magazine and the associated mold conveying device allow gen, the cover plate to the formation of 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 prefer tes method is that you the cover sheet with weakening lines before the edge 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 cover, at least one line of weakness is provided which runs between two adjacent cover corners and follows a path that follows

■ • ο when leaving a corner of which the two corners connecting portion of the molded edge diverges and when approaching the other corner to this Edge converges. The course of the line can comprise several straight sections, with

<5 adjacent straight sections a sharp kink 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 lines of weakness. This gives you a relatively flat one Area with a gentle curve downwards towards the corners; one restricts the weakening lines to the areas around the perimeter, one can achieve an advantageous design in all areas the cover plate after the tension reduction tion serving bulge along the weakening lines lie within the volume enclosed by the cast-on edge. This allows the Composite lids are handled on conventional machines, where they are taken from the stack and then be placed on the filled shafts; these machines cannot use composite lids in all cases handle with the top panel bulging past the top of the rim, d. H. if the

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

The composite lids can be used for closing molded or cast containers are used, which in the usual way have a bottom and Have 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

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 is III-III and IV-IV in Figs. 1 and 2;

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

F i g. 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-VIH in FIG. 7th

The composite lid according to FIGS. 1 and 3 has a substantially square top plate 1 made of a first material serving as a carrier material, e.g. B. cardboard and an edge 2, which around the circumference of the cover plate made of a second material, for. B. Polyethylene is molded or cast. The outer leg 4 extends the furthest and has an integrally formed locking tongue 5. The inner, shorter leg 6 has a flange protruding at right angles v> 7, which is directed away from the outer leg. The four corners 8, 9, 10, 11 are rounded. The top plate has correspondingly rounded corners and upwardly bent tabs 12 along each edge. Between adjacent corners, ie between corners 8 and 9, 9 and 10, 10 and 11 and 11 and 8, weakening lines 13 each consist of two straight sections which meet to produce a sharp bend 14. Each line diverges when it leaves its corner from the section of the molded edge 2 connecting the two corners and converges towards the edge when it approaches the other corner. The cover plate is bent along the line 13, so that the one shown in FIG. 3 evident concave or plate-like profile

A composite lid according to FIGS. 1 and 3 is produced by lid plating that 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. Those that are still level or flat Cover plates are fed to a casting mold in which the edge around the cover plate is injection molded is formed, the edge tabs are bent open as shown in the drawings. At the When removed from the mold, the top plate automatically bulges along the lines of weakness around the Relieve tension that has built up in the top plate due to the contraction of the edge during cooling

The in the F i g. The composite lid shown in FIGS. 2 and 4 is essentially the same as that in FIGS. 1 and 3 except χ Al (for corresponding parts the same reference numerals have been selected), that the weakening lines 21 form weicnc curves instead of straight legs. In the case of both composite covers, an inner region 22 is provided which is at a distance at all corners and is free of any lines of weakness. This results in a relatively flat area with a curvature gently downwards towards the corners. As one can see from FIGS. 3 and 4, this means that all areas of the cover plate lie within the volume which is enclosed by the molded edge, the upper and lower edges 23 and 24 in these cuts to one or the other side of the cover plate point.

The Fig.5 and 6 show a composite lid, the similar to the previous one, except that all lines of weakness 51 meet each other in the middle. As a result, the cover plate arches 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 the F i g. 7 and 8 is a triangular one Composite lid shown, which illustrates how the invention applies to other than the usual square or rectangular shapes can be used. Here, too, parts that corresponded to one another were identical Reference symbol chosen.

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, thereby characterized in that the cover plate is 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. Z Method according to Claim I _1, characterized in that the lines of weakness are applied to the cover plate before the second material is cast on 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.