Hinges

Abstract

A one-piece hinge formed of plastic material, movable about an axis from a closed and open position is disclosed, the hinge including two hinge plates interconnected by a web which lies in one axis, at least one slit arranged at right angles to the axis separating the web into two or more hung strips, one of the strips being grooved at the position of the axis, another hinge strip acting as a tension spring to bias the hinge into its closed and open positions also including a spring portion thereof having an undulating from in both the closed and open positions and displaceable about two additional axes parallel to but at points offset from the first axis.

Description

This invention concerns improvements in or relating to hinges. More particularly, the invention is concerned with hinges moldable in one-piece from so-called "plastic" material, that is to say from natural or synthetic resins, and which are for instance especially suitable for mounting the lid upon the body of an injection-molded plastic container. Such hinges consist essentially of a groove in the plastic material between the hinge plates, which enables the inherently flexible plastic material to bend in a hingelike manner along the line of the groove.

It is known to furnish one-piece plastic hinges of this type with a spring which normally holds the hinge in the closed position, thus for instance holds the lid upon the body; and which is tensioned as the hinge is swung back, thus for instance as the lid of the container is opened. This arrangement, however, requires the provision of a separate tension spring whose ends must be secured to the respective hinge plates. It is also known to make one-piece plastic hinges, for instance by injection-molding or extrusion techniques from polypropylene or other plastic materials, in such a way that the inherent resilience of the plastic material in the region of the groove constituting the hinge, which is elastically deformed whenever the hinge plates are swung away from the original position in which they were formed during manufacture, tends always on release of the hinge plates to return them automatically to their original position. This tendency, however, is restricted by the weight of the hingedly interconnected parts, by frictional forces and indeed possibly by other resistances to movement. It is, moreover, difficult if not impossible so to manufacture the hinge in this way that it exerts a positive bias to close the hinge, and thus for instance to hold the lid positively upon the body of the container.

However, one-piece plastic hinges are already known, which possess a positive hinge-closing bias. These one-piece plastic hinges, known under the name Mira-Gelenk, have two hinge strips, separated by a slit and extending parallel to each other at right-angles to the hinge axis (in the sense of the axis about which the hinge plates are to swing), these hinge strips being each grooved generally in the direction of the hinge axis to constitute the hinge, but with the grooves in the respective hinge strips slightly offset relative to one another. With this arrangement, due to the offset between the direction of the grooves in the respective hinge strips, the spring plates can be opened only by deforming the resiliently flexible plastic material from which the hinge is made so as to bring the grooves in the respective strips into line with the hinge axis. Consequently, this construction possesses a positive hinge-closing bias. Unfortunately, however, this known construction possesses certain disadvantages. It can be manufactured only by injection-molding with the hinge plates aligned almost precisely in the 180.degree. -open position. Moreover, although this construction does impart a positive hinge-closure effect, the force with which that closure can be effected cannot be very great, usually no more than that occasioned by a 12.degree.-..degree. deflection from the natural rest position, since otherwise the inherent resilience of the plastic material will be overstrained and become weakened. Furthermore, hinges of this construction have projecting edges, and require a slit between the hinge strips of 0.8 to 1 mm. width, which often is undesirable in containers. Finally, there are various manufacturing difficulties. Containers of rectilinear cross section can be made only with difficulty if provided with a hinge of this type. The injection-molding equipment must be most accurately constructed and operated, since with the plastic materials usually employed the thickness of the hinge at its thinnest point adjacent the groove must be only 0.25 to 0.35 mm. Furthermore, where two or more hinges are provided adjacent one another between the lid and the body of a container, it is essential that these adjacent hinges must be exactly similar.

It is an object of the present invention to provide a novel construction of one-piece plastic hinge generally superior to those heretofore available, and which in particular is easy to manufacture, possesses a strong, positive hinge-closing action, and is well adapted for use in containers of rectilinear cross section.

According to the present invention, there is provided a one-piece hinge formed of inherently flexible, resilient, plastic material, comprising two relatively thick and inflexible hinge plates separated but innterconnected by a relatively thin and flexible joint constituting the hinge axis, in which the hinge is separated by one or more slits arranged generally at right-angles to the hinge axis into at least two hinge strips, one of said strips being grooved along the hinge axis and defining the same, another of said hinge strips having hingelike axes formed by material thinning at each of its ends, said hingelike axes extending parallel to the hinge axis and inter connecting the hinge plates at points offset from the hinge axis with the respective ends of the intermediate portion of said other hinge strip, said intermediate portion having at least one relatively thin, resiliently flexible corrugated section extensible longitudinally as the hinge plates are swung from their closed to their open position.

The intermediate portion of the other hinge strip which functions as a tension spring to bias the hinge in to its closed position can be formed of relatively thin and hence resiliently flexible material and can be corrugated throughout its entire length. However, it is much preferred that this intermediate portion shall include a central, relatively thick and inflexible section surrounded by two relatively thin, resiliently flexible corrugated sections. Conveniently, the intermediate portion overall either can have the form of a capital letter omega or can consist of a central relatively thick section similar to that constituting the hinge plates surrounded by relatively thin and flexible U-shaped sections.

The hinge constructed according to this invention possesses a snap-action, that is to say it is held positively by the resilience of the corrugated section(s) of the intermediate portion of the hinge strip in either its open or its closed position, and passes as it is swung between those open and closed positions through a metastable intermediate position in which the resiliently flexible corrugations are stretched to their full extent. If the hinge axis of one of the hinge strips and the attachment points between the corrugated hinge strip and the hinge plates in the same plane, normally the median plane of the hinge plate, then the opening angle of the hinge (i.e., the angle which it makes, in open position, with the metastable intermediate position) will be the same as its closing angle (i.e., the angle which it makes, in a fully relaxed closed position, with the metastable intermediate). If it is desired that the opening and closing angles of the hinge should be different, this can readily be achieved by locating the hinge axis in one hinge strip about which the hinge plates swing in a different plane (located in the common plane of the hinge plates) from the plane (also lying in the common plane of the hinge plates) of the attachment points connecting the hinge plates to the other hinge strip. For this purpose it may also be convenient to arrange that the attachment points interconnecting this other hinge strip with the respective hinge plates are offset by significantly different distances from the hinge axis in the first-mentioned hinge strip about which the hinge plates swing.

The hinge according to this invention can consist of only two hinge strips, as so far described. However, it is generally preferred that the hinge should consist of at least two and advantageously a plurality of hinge strips of the first-mentioned type, arranged alternately along the hinge axis with hinge strips of the second-mentioned type. It is, moreover, also preferred that the two hinge plates should each be moulded integrally into and form part of a container, thus respectively the container body and the container lid, so that the whole container including the hinge between lid and body may be injection-molded in one piece.

According to requirements, the container including the hinge should be so molded that the lid of the container engages with the body of the container before the hinge has reached its fully closed position, and thus before the corrugations in the appropriate hinge strips have reached their fully relaxed condition, so that the lid is thereby positively held in the closed position by the resilient bias of the corrugated hinge strip. Unlike the previously known construction, it is possible to injection-mold the hinge according to this invention with the hinge plates arranged at an angle of 45.degree. . The force with which the closure is effected can be varied from weak to strong, simply by suitable choice of the thicknesses and dimensions of the various parts, as well as naturally also the material from which they are made. It is possible by making the parts thin and consequently elastic to secure a closing force equivalent to a deflection from the relaxed position of as much as 30.degree. . Since the corrugation in the corrugated hinge strip can easily be kept (naturally, when the hinge is in the closed position) within the outer contours of the hinge (defined by the normal-type hinge strips) there are no projecting edges. The slit separating the hinge strips can be kept to a minimal width, of about 0.1 mm., merely sufficient to permit the hinge strips to slide past one another, and consequently the slit becomes practically imperceptible. The hinge according to the invention can be used to secure the lid to the body of even a rectilinear container, since the outer contours of the hinge can be identical to those of the container when the lid is in the closed position. It will, moreover, be appreciated that no excessive precision is required in injection-molding techniques when manufacturing containers with the hinges in accordance with the invention.

In order that the invention may be well understood it will now be described in more detail, though by way of illustration only, with reference to the accompanying drawings, in which:

FIG. 1 shows a plan view of one preferred embodiment of a one-piece hinge manufactured in accordance with the invention from plastic material;

FIG. 2 shows a view, partly in elevation and partly in cross section, of the same embodiment, taken along the line I--I in FIG. 1, showing the hinge in closed position;

FIG. 3 shows a view similar to that of FIG. 2, but with the hinge in its metastable intermediate position;

FIG. 4 shows a view similar to FIGS. 2 and 3, but with the hinge in open position;

FIG. 5 shows a view, partly in elevation and partly in cross section, generally similar to that of FIGS. 2-4, but of another embodiment of hinge according to the invention, in closed position; and

FIG. 6 shows a similar view of the same embodiment as shown in FIG. 5, but with the hinge in open position.

Referring to FIGS. 1 to 4, it will be seen that the hinge comprises two hinge plates 1 and 2, interconnected via two hinge strips 3 and 4, each of these hinge strips 3, 4 being grooved on both faces (at 5 and 6 respectively) to define the hinge axis. The hinge strips 3 and 4 are separated respectively by slits 7 and 8 from an intervening hinge strip (identified in FIG. 1 as 9) which--as can best be seen in FIGS. 2-4--comprises a central, relatively thick and inflexible section 9' , whose ends are linked respectively to hinge plates 1 and 2 by relatively thin and hence flexible U-shaped corrugations. The hingelike axis of these corrugations are marked respectively 10 and 11.

FIG. 2 shows the hinge in its closed position, in which hinge plate 1 is held in the desired position relative to hinge plate 2 about the hinge axis by the corrugated hinge strip 9, which (as shown) is in its relaxed, unstretched condition--or which may be under slight tension, if a positive closing force is required. In order to move the hinge to its open position, hinge plate 1 must be swung about the hinge axis into the metastable position shown in FIG. 3. Here the U-shaped corrugations in hinge strip 9 are fully stretched, and thus due to their inherent resilience exert the maximum tension on hinge plates 1 and 2 about the hinge axis. Once the hinge plate 1 is moved past this metastable position, the tension exerted by the stretched U-shaped corrugations snaps the hinge into the open position shown in FIG. 4. Here the U-shaped corrugations have again assumed their relaxed, unstretched shape, and their natural resilience will retain the hinge plate 1 in this open position, unless a positive closing action is undertaken.

It will be noted that in FIG. 3 the attachment points between corrugated hinge strip 9 and respectively hinge plate 1 and 2 have been indicated as 12 and 13. These in the metastable position of the hinge shown in FIG. 3 lie in a plane with the hinge axis, defined by groove 5. As shown in FIG. 3, this plane is the median common plane of the hinge plate 1 and 2, consequently the opening and closing angles of the hinge (shown respectively in FIG. 2 and FIG. 4) are the same. If, however, the hinge axis 5 and the attachment points 12 and 13 do not lie in the median common plane, then the opening and closing angles of the hinge will be different.

In FIGS. 5 and 6 there is shown a hinge particularly intended to be integrally molded with both the body and the lid of a container. Here the hinge plate 15 forms part of the container lid, and hinge plate 16 forms part of the wall of the container body. The hinge axis between lid and body, indicated at 17, is constituted by a groove (see especially FIG. 6) in hinge strip 18. The lid 15 is held in the closed position shown in FIG. 5 by corrugated hinge strip 14, having a second central section 14' ,which overall has the shape of a capital letter omega It can clearly be seen, by a comparison of FIGS. 5 and 6, that--because the hinge axis 17 lies on one side of the median common plane of the hinge plates 15 and 16 while the attachment points between the hinge plates and the respective ends of the corrugated hinge strip 14' lie on the other side of the median common plane--the opening and closing angles of the hinge are different.

FIGS. 5 and 6 show the hinge in its respective extreme positions, that is to say when the corrugations are as fully relaxed as possible. Thus, in this extreme closed position shown in full-line in FIG. 5 the container lid, while retained in the closed position by the resilient flexibility of the corrugated hinge strip 14, is not positively forced into engagement with the container body thereby. However, it is sometimes advantageous to hold the lid upon a container by a positive force. For this purpose, the hinge should close the container before the hinge itself has reached a fully closed position. This is illustrated in FIG. 5 in dotted lines. The lid 15 is brought into engagement at this position with the container body, and thus before hinge strip 14 is fully relaxed, so that the latter positively holds the lid in engagement therewith.

It will be understood that, in order to secure the difference between the opening and closing angles of the hinge, relative to the common plane of the hinge plate, it is possible to alter the separation between the hinge axis, defined by the groove 5 in FIGS. 2-4, and the attachment points between the ends of the corrugated hinge strip and the respective hinge plates, thus for instance points 12 and 13. In principle, the same result is then secured as has been described above in relation to a shift of the hinge axis and of the attachment points out of the median common plane of the hinge plates.

While two preferred embodiments of the invention have been described above in detail, it will be well understood by those skilled in the art that various modifications and alterations can readily be made within the scope of the present invention.

Claims

It is claimed:

1. A one-piece hinge formed of plastic material, and moveable about a first axis between closed and open position, comprising:

two hinge plates interconnected by a web in which lies the first axis,

one or more slits arranged generally at right angles to the first axis and separating said web into at least two hinge strips,

one of said hinge strips being grooved at the position of said first axis,

the other of said hinge strips being adapted to function as a tension spring to bias the hinge into its closed, and open, positions and including a spring portion displaceable about two second axis parallel to, but at points offset from, said first axis,

said spring portion having at least one section which is extensible longitudinally as the hinge plates are swung from their closed position to their open position, which has an undulating form in both the closed and open positions such that tension is maintained in a direction longitudinal to said spring portion.

2. A hinge as in claim 1 wherein said spring portion has a thickened section intermediate two other sections of comparatively reduced thickness.

3. A hinge as in claim 2 wherein said thickened section is positioned centrally between the two other sections, which both have an undulating form.

4. A hinge as claimed in claim 1 in which the spring portion has the overall form of a capital letter omega

5. A hinge as claimed claim 1 in which the distances separating the attachment points between the hinge strip from the hinge axis are different.

6. A hinge as claimed in claim 1 in which the hinge axis and the attachment points lie in the median common plane of the hinge plates when the hinge is in its metastable intermediate position.

7. A hinge as claimed in any of claim 1, in which both the hinge axis and the attachment points lie outside the median common plane of the hinge plates and on respectively opposite sides thereof when the hinge is in its metastable intermediate position.

8. A hinge as claimed in claim 1, comprising a plurality of said one and said other hinge strips, arranged alternately along the hinge axis.

9. A one-piece hinge formed of inherently flexible, resilient plastic material, said hinge comprising:

two relatively thick and inflexible hinge plates,

at least one first hinge strip connecting said plates and having a groove formed therein to define a hinge axis about which said plates are rotatable, and

at least one second hinge strip longitudinally displaced along said hinge axis from said first hinge strip and also connected between said plates but at offset connection points offset from said hinge axis,

said second hinge strip including at least one undulating springlike section which provides a tension force between said offset connection points to bias said hinge plates to one of its open and closed stable positions.