GB2051219A

GB2051219A - Hinges in Elongated Plastics Bodies

Info

Publication number: GB2051219A
Application number: GB7933396A
Authority: GB
Original assignee: Breveteam SA
Current assignee: Breveteam SA
Priority date: 1978-09-27
Filing date: 1979-09-26
Publication date: 1981-01-14
Also published as: DE2936863A1

Abstract

An elongated body 1 made of a plastics material which undergoes cold-working when subjected to bending has at least one latent or potential hinge formed by a weak point 3 in its cross-section defining a web in which initially the molecules of the plastics material are unoriented and unstrengthened. The weak point may be formed by a groove 2 or a notch 29, 30 or lines of holes 35. When it is desired to form a hinge in the body it is bent back and forth once or repeatedly at the weak point, resulting in thinning and strengthening of the material of the web. The material may be a polyolefin such as a polypropylene or a polyester or polyamide, or an ABS resin. <IMAGE>

Description

SPECIFICATION Elongated Plastics Bodies The invention relates to a body made of a plastics material which undergoes cold working when subjected to bending.

It is already known (Vieweg/Schley/Schwarz, "Plastics Handbook", volume IV, Polyolefins, Carl Hanser Press, Munich, 1969, pages 483 and 817/818), to connect two moulded components by means of a hinge formed by a web of polypropylene, that is to say, by means of a flexible but not detachable connection. In this construction the hinge is formed as a thin film between the moulded components on injection moulding of them. By cold-working when subjected to bending, the hinge web only then acquires the necessary strength so that it can withstand alternating loads. The formation of the known web hinge by an injection moulding process requires expensive steps and a special construction of the mould so that the hinge is produced in its finished and final form between the two components and without a damaging influence on the latter.

A strip hinge of plastics material is also known with a central groove extending over the whole length of the strip to define the hinge web. (DE AS 1 479 620). The web already pre-shaped on extrusion, is subsequently shaped further while the plastics material is still soft, by displacing the excess plastics to the desired extent. The known hinge is accordingly already present in the coldworked and thereby orientated condition of the molecules of the plastics material transverse to the groove, and thus already has all the characteristics of a finished hinge. Expensive steps are necessary in its formation in order to achieve the desired strength of the web in the respective operation steps. The need for matching the shape of the extrusion nozzle to the desired shape of the hinge also does not permit the formation of a hinge of different shape.The known strip hinge must also first be attached for its pre-determined purpose to components that are to be pivoted together.

It is generally known that a substantial effort is required to bend back or fold bodies of plastics material transverse to their direction of longitudinal extent. Generally the flexing cannot conveniently be performed at any desired point and it requires for a particular desired direction of bending, a more-or-less effective controlling support, for example the user's hand or engagement or support by auxiliary means, for example by bending over a rigid edge.

The aim of the invention is to provide a body of plastics material of the kind referred to in the introduction above but without the drawbacks of the previously known bodies of this kind, and which can be brought into use with substantially minimal exertion of effort and can, without complicated support, be brought to another desired shape by bending in a predetermined direction, and in which, by the employment of a material which undergoes cold-forming when bent, at least at part portion of the body can be brought into another position with respect to the other part, whilst maintaining the connection between the two parts, the part being freely moveable about a newly formed axis with respect to the other part.

To achieve this result, according to the invention a body of the kind stated in the introduction above is characterised in that it has at least one weak point in the cross-section of the body, by which the body is divided into sections and which can be strengthened, with the formation of a hinge, by bending back at least the one section.

In our co-pending British Patent Application No. 79..., filed simultaneously with the present application, there are described elongated bodies of plastics materials which are provided with grooves or recesses that weaken their crosssections and by which they can be bent. However, the recesses, which are round, do not extend over the whole width of the strip, so that when the strip is detached from a plate by tearing, it is prevented from tearing along a path, transverse to the direction of separation and passing through the recesses.

By the phrase "weak points", there should also be understood, in the following, a weakening at which the molecules of the plastics material are substantially non-oriented and not yet coldworked, that is to say, are present in an unstrengthened condition and by which the hinge in itself is not yet formed but is present in a potential or latent form. Only when at least one alternation of load takes place, by bending back at the weak point, is there cold-working and orientation of the molecules and thereby the formation of the hinge having the desired strength characteristics. The weak point has, for example, a minimum thickness which decreases after a number of cycles of bending back and forth but still results in a sufficiently lasting hinge web.

By the provision of the weak points in the body according to the invention the body can be converted, with the formation of the hinge by bending, from its original shape, for example elongated or extended, into another desired shape or form. Thus there exists a moulded body which, by virtue of the presence of the latent hinge retains its original form, that is to say its sections remain in their original predetermined relative positions. By bending, with the formation of the actual hinge, another shape can be formed, in which, by virtue of the presence of the hinge or hinges now present, the sections are freely movable relative to one another and which is flexible in itself and from which can be formed a different shape with the formation of the hinge.

The weak point, that is to say the latent hinge, can preferably be of such a form that the crosssection is weakened by actual displacement or removal of material. The displacement of material can be achieved by embossing, drilling, punching, milling, slotting, sawing or shaping and for example in the manufacture of the plastics body itself, for example by extrusion or injection moulding, or subsequent to manufacture. The formation of the weak point is achieved for example at a temperature at which there is no orientation or cold working of the material. Where polypropylene is used, for example, as the coldworking material, the weak point can be formed for example by pressing at temperatures above the softening point of the material, for example at 1800C.

Wherematerial is actually removed, this can be done by forming a recess, for example, a round bore right through the thickness of the body, the dimensions of which, for example the diameter of the hole, can be less than the width of the body.

In this way orientation and cold working of the molecules of the plastics material can be conveniently avoided. The body can at will be provided with a selected number and shape of weak points according to the use envisaged.

Bending of the sections separated by the weak points allows the body to be employed as a shaped body for various purposes.

The-body according to the invention can be in the form of a strip or bar or a predetermined section and after bending at the weak point can be used for example for securing sheets on a substrate, for example on the ground or in sheets of foam material or the like, or for securing tags or notices or the like to packages, such as for example food packs, as described by way of example in our co-pending Patent Application filed simultaneously with the present one.

Another possible use for the body is as a conveyor belt or driving belt, with an appropriate number and placing of weak points.

The weak points can be formed already by a round recess extending over part of the width of the body, as described in our above-mentioned co-pending Application and can be produced in a simple manner, for example by embossing or stamping. In order to avoid tearing or breakage by bending at non-weakened points, which can arise when the body is handled at temperatures below room temperature, for example less than OOC, the weak point preferably extends over the entire width of the body transverse to the direction of its length. Accordingly the round recess preferably has a diameter equal to the width of the body. In one embodiment of the invention the weak point can be a weakening band which extends for example at right angles or for example at an angle of almost anything between 0 and 900 to the length of the body.In this way it is possible for one portion of the body to be bent in a perpendicular or other desired direction of bending with respect to another portion. For example a channel-shaped recess can be formed by means of which the weak point is formed in an advantageous and simple manner by a reduction in the cross-section of the body. Several weak points can be present, lying parallel to one another, so that, looking in the direction of the length of the body, there are for example alternate weakened zones and unweakened zones. The weak points could follow meandering paths so that, when subjected to bending, a number of hinges are formed, to result in a flexible body, which for example can be used as a conveyor belt or driving belt.

In one embodiment of the invention the weak points can lie on opposite faces of the body.

However the weak point could also be a constriction which, for example, is defined by a notch or notches extending in from one or both side edges of the body.

A number of bodies according to the invention could be incorporated in a plate as individual articles, separable from one another by means of channel-shaped grooves penetrating nearly through the thickness of the plate to leave only a residual thin web and the individual articles having the weak points. The thin web is preferably capable of being torn, as described in our abovementioned co-pending Application.

The cold-working material of the body according to the invention preferably has sufficient crystallinity for achieving the formation of the hinge and can be a polyolefin for example polypropylene, a polyester or polyamide or an ABS resin.

The invention is further explained by way of example in the following in conjunction with the drawings, in which:~ Figure 1 shows a plastics body diagrammatically in plan view; Figure 2 shows a longitudinal section through the body of Figure 1 on the line Il-Il in Figure 1.

Figure 3 shows the body of Figure 1 in side elevation in another shape; Figure 4 shows diagrammatically another body of plastics material in plan view; Figure 5 is a longitudinal section along the line V-V in Figure 4; Figure 6 shows diagrammatically a longitudinal section through a further body of plastics material; Figures 7 to 14 each show diagrammatically a further body in a plan view; Figure 15 is a longitudinal section through the body of Figure 14, taken along the line XV-XV in Figure 14; Figure 16 is a diagrammatic plan view of a plate of plastics material; Figure 17 is a perspective diagrammatic illustration of a plate comprising several bodies; Figure 18 shows diagrammatically a plan view of a further body; Figure 19 shows a layout of bodies in a plan view; and Figure 20 shows one use of the bodies of Figure 19.

Referring to Figures 1 and 2, an elongated body 1 of plastics material which includes a material which is capable of cold working when subjected to bending and can for example be manufactured from polypropylene, has channelshaped notches or grooves 2 which are arranged parallel to one another and perpendicular, to the longitudinal extent, identified at L, of the body.

The notches 2 extend over an overall width B of the body 1 which is less than its length L. As shown in Figure 2, the notches 2 have a depth T which is less than the thickness D of the body so that weak points 3 of thickness C remain at the bases of the notches 2. The notches 2 and weak points 3, in which the molecules of the plastics material are unoriented and not cold-worked, divide the body 1 into sections 5, 6, 7 and represent latent or potential hinges which, as shown in Figure 3, are brought into existence by bending of the sections 5 and 7 back and forth in the direction of arrows A about the respective weak points 3 as a pivoting point, strengthening the material at the weak points 3 to form hinges 8. Accordingly there is formed from the body 1 by bending of the sections 5 and 7 with respect to the central section 6, a shaped body 9 of different form.By repeated alternation of the load in bending the hinges 8 can be strengthened further and made ever thinner.

Preferably the thickness D is less than the width B of the body 1, which can be between 1 and 1 Omm so that the body 1 is a flat bar-like shape, that is to say, in the form of a strip or plate.

The depth T of the notches 2 is chosen so that the thickness C of the weak points is sufficient to form hinges 8. Where the thickness D of the body 1 is between 2 and 1 Omm, the thickness C is for example 0.1 to 1 mm. The notches 2 can have a width E of, for example, 0.5 to 1 Omm. By repeated bending back and forth the necessary strength and a desired ease of movement are achieved.

Referring to Figures 4 and 5, a body 11 has a round recess 12 of which the diameter F corresponds to the width G of the body 1 1 so that there is a weak point 13 at which a hinge is formed by bending in the direction of arrow H, transverse to the longitudinal axis K.

As shown in Figure 6, weak points 17 are formed on opposite faces 14 and 15, namely the upper and lower faces, of a body 16, these weak points being in the form of pointed conical recesses 18, and they extend over the whole width of the body. The weak points 1 7 are again capable of being strengthened to form hinges by bending back transverse to the longitudinal extent of the body 16.

A body 19, shown in Figure 7, has weakening bands 20 which extend parallel to one another and are transverse to the direction of longitudinal extent, identified by the axis M, of the body, being inclined at an angle to that axis, this angle being between 0 and 90 , so that, looking in the longitudinal direction, there are alternate weakened zones and unweakened zones.

In a body 23, shown in Figure 8, there are weakened bands 24 of meandering form so that all or selected hinges are formed by bending, producing from the body 23 a new shape having flexibility which can be chosen at will.

Figure 9 shows a body 25 of width N, having notches 29 in its side edges 26 and 27 which extend transverse to the broad faces 28 (only one is shown), that is to say its upper and lower faces, these recesses defining a constriction 30. The constriction 30 weakens the cross-section of the body 25 so that again a latent or potential hinge 31 according to the invention is formed.

Figure 10 shows a body 32 with a widened central portion 33 having weakening bands 34 in the form of a row of round recesses 35 extending over the whole width P of the central portion 33, and again forming a latent hinge according to the invention.

As shown in Figure 11, latent hinges 34a can also be formed by rows of round recesses 35a which, in the same manner as in the embodiment of Figure 7, are inclined at an angle transverse to the longitudinal axis LB of a body 32a of plastics material.

As shown in Figure 12, latent hinges 34b can be in the form of recesses 35b arranged in a meandering line in a body 32b: in this way one can select hinge bends with quite unusual combinations of angles.

Figure 13 shows a body 23a provided with several latent hinges made up of intersecting weakening bands 24a which can be formed by grooves. The body 23a can be bent back in any direction corresponding to the latent hinges and hinges can thus be formed at any desired points.

A body 1 la shown in Figures 14 and 15 has a round hole 1 2a right through its thickness GA and having a diameter DA which is less than the width BA of the body 1 1 a. The webs 1 3a that are left form a latent hinge.

Figure 16 shows an elongated plate 36 made of a plastics material capable of cold-working when subjected to bending and having a weakening band 37 by which a latent hinge according to the invention is formed. The band 37 extends in a direction transverse to the length R of the plate 36 and over the whole width S of the plate so that for example the one part 38 of the plate 36 can be bent back with respect to the other part 39 in the plane of the drawing, forming a hinge. For example printing and/or a picture can be applied to a region 40 of the part 39 and the bent-back part 38 can be used for mounting. This possibility allows one also to produce frames for cheap glasses.

Figure 17 shows how several bodies 41 can be combined in the form of a plate 42 in which the bodies are separated from one another in their longitudinal directions U by channel-shaped grooves 43 and are connected together by thin webs 44 at which the bodies 41 can be separated from one another, for example by tearing. The bodies 41 can for example be consumer articles as described in our above-mentioned co-pending Application. Each body 41 has weak points 46 formed by grooves 45 extending transverse to the longitudinal direction U and over the whole width V of each body 41, thus forming latent hinges according to the invention. The weak points 46 are thicker than the webs 44 so that bending back and forth produces a hinge and not tearing or breakage, as is the case with the webs 44.After a body 41 has been detached a hinge can be formed by bending back at the weak points 46 and the body 41 can be formed into a new shape.

By virtue of the bodies 41 making up the plate 42 the bodies complete with the weak points 46, can be manufactured conveniently in a one step, for example by extrusion or injection moulding and subsequent formation of the weak points 46.

As shown in Figure 18 it is also possible to provide a strip shaped body 47 in its longitudinal direction UA with differently shaped recesses 48, 49 or 50 to form latent hinges. The recesses 48 and 50 are in the form of holes which extend through the whole thickness of the strip 47. The strip 47 can for example be attached to an article at one of the recesses 48, for example by means of a screw, and bent back at selected points at which the latent hinges are present.

As shown in Figure 19 a number of strips 51 can be arranged in a plate 52 to be capable of detachment by tearing off, and have latent hinges in the form of holes 53. When two interconnected strips 51 have been detached they can be used for connecting a door 54 to a wall 55, as shown in Figure 20. Two of the holes 53 are used for mounting by means of screws 56, whilst the remaining hole 53 is formed into a hinge by repeated bending back and forth, resulting in the formation of a door hinge.

The body 47 can be employed in various ways.

One can maintain the latent hinge in its originally formed shape and use the body in this form. One can bend it back only once at a selected latent hinge and use it in this form; still substantially rigid, but of a shape different from its original shape. By repeating bending back and forth one can however also form a hinge at a selected point.

However, as indicated, one can also use one or more of the holes 48 or 49 simply for example for screwing it in place.

The above mentioned reduction in thickness of the weak points can be explained as follows: Where the body has a thickness of 2.8mm and where the weak point has a thickness of 0.95mm, the weak point becomes reduced in thickness, after a single bending, to a thickness of 0.25mm.

After, bending back and forth for example 300 times, the hinge becomes further reduced in thickness only to 0.20mm.

Claims

1. A plastics body including plastics material which undergoes cold working when subjected to bending, distinguished by the feature that at least one weak point is present in the cross-section of the body, by which the body is divided into sections and which by bending of at least one section about a bending axis is capable of being strengthened to form a hinge.

2. A body according to Claim 1 in which the weak point consists of unoriented and unstrengthened molecules of the plastics material.

3. A body according to Claim 1 or Claim 2 in which the body is of elongated shape and the weak point is capable of being strengthened by bending back transverse to the longitudinal direction of the body.

4. A body according to Claim 3 in which the weak point extends over the entire width of the body.

5. A body according to Claim 3 in which the weak point is a weakening band.

6. A body according to Claim 5 in that the weakening band extends at right angles to the direction of longitudinal extent of the body.

7. A body according to Claim 5 in which the weakening band extends at an angle of between 0 and 900 to the direction of longitudinal extent of the body.

8. A bddy according to any one of Claims 1 to 3 in which the weak point is formed by a reduction in the cross-section of the body.

9. A body according to Claim 8 in which the weak point is formed by a channel-shaped groove.

10. A body according to Claim 8 in which the weak point is formed by a round recess of which the diameter corresponds to the width of the body.

11. A body acccording to Claims 1,2 or 3 in which several weak points are present, following a meandering path.

12. A body according to Claim 3 in which, looking in the direction of the length of the body, alternate weakening zones and unweakened zones are present.

13. A body according to Claim 1,2 or 12 in which several weak points are present, extending parallel to one another.

14. A body according to Claim 1 or Claim 2 in which the weak point is defined by recesses on opposite faces of the body.

15. A body according to Claim 1 or Claim 2 in which the weak point is formed by a hole passing right through the thickness of the body and having dimensions less than the extent of the surface of the body.

16. A body according to Claim 15 in which the hole is round and its diameter is less than the width of the body.

17. A body according to any one of Claims 1 to 14 forming part of a plate made up of individual bodies separable from one another, the bodies being separable by means of channel-shaped grooves penetrating nearly the thickness of the plate to leave only thin residual breakable webs, capable of tearing, and the bodies having the said weak point or points.

18. A body according to any one of Claims 1 to 17 in which the material which is capable of cold working is a polyolefin, for example, polypropylene, polyester or polyamide or an ABS resin.

19 A body according to Claim 1 or Claim 2 in which the weak point is a constriction defined by notches extending in from at least one longitudinal side of the body.

20. A body according to Claim 1 or Claim 2 in which there is displacement of the material at the weak point.

21. A body according to Claim 1 or Claim 2 in which there are several weak points with their axes arranged at different positions from one another.

22. A method of forming a hinge in a body of plastics material capable of cold-working, comprising providing the body with at least one weak point in its cross-section, of substantially unoriented and unworked material and then strengthening this point by bending back about a bending axis to form a hinge web.

23. The method of Claim 22 in which the weak point is formed by reduction in the cross section of the body with displacement of the material, for example by embossing, drilling, punching, milling, sawing, slotting or shaping.

24. The method of Claim 22 in which the weak point is formed by a hole penetrating through the whole thickness of the body and having dimensions less than the extent of the surface of the body.

25. The method of any one of Claim 22 to 24 in which the weak point is formed at a temperature at which orientation of the molecules of the plastics and working of the material do not take place.

26. The method of Claim 22 in which the weak point is strengthened by bending along a line transverse to the direction of longitudinal extent of the body.

27. The method of Claim 26 in which the bending line is perpendicular to the direction of longitudinal extent.

28. The method of Claim 22 applied to a body of a polyolefin material capable of being cold worked, for example polypropylene, a polyester, a polyamide or an ABS resin.

29. A body of plastics material which undergoes cold working when subjected to bending, substantially as described with reference to any one or more of the accompanying drawings.

30. A method of forming a hinge in a body of plastics material which undergoes cold working when subjected to bending, substantially as described with reference to the accompanying drawings.