DE2652617A1 - ITEMS THAT CAN BE RECOVERED - Google Patents

Description

The invention relates to heat recoverable articles, particularly heat shrinkable wraps.

By heat-recoverable article is meant herein an article which has been deformed from its original configuration to a second configuration and which is able to return to or towards the original configuration by the application of heat alone. Such heat-restoring articles are well known and in their most common form represent a heat-shrinkable sleeve made of a polymeric material to which the property of plastic or elastic memory can be imparted. This sleeve is expanded to a larger diameter than the normal diameter at an elevated temperature and then cooled while it is held at the enlarged dimension. A sleeve treated in this way retains its expanded dimensions until it is reheated, whereupon it reverts to its original shape. Examples of plastic materials suitable for making such heat recovery articles can be found in US Pat. No. 2,027,962 and US Pat. No. 3,086,242.

In other heat-resilient articles, such as those described in GB-PS 1.440.524, an elastic member is held in the expanded state by another member which loses its strength, e.g. melts when the temperature is increased and thereby the elastic member allows to return to the unexpanded state.

Finally, it has recently been shown that certain alloys, sometimes referred to as "memory metals", also have the property of heat recovery. In this context, reference is made, for example, to the nickel-titanium alloys that are described in NASA publication SP 5110 "55-Nitanol - The Alloy with a Memory, etc." (US Government Printing Office, Washington DC, 1972), as well as the small beta brass alloys described by N.Nakanski et al in "Scripta Metallurgica" 5, 433-440 (Pergammon Press 1971), and the stainless steels described by E. Enami et al, loc. cit., pp. 663-668.

Heat shrinkable sleeves are used particularly in the connection and termination of wires, cables and pipes. However, there are many examples where termination, insulation or protective end closure is desired for elongate objects such as cables and pipes, where the ends of the elongate object are inaccessible, or if they are accessible, they are undesirable to separate or otherwise remove from their original position. So-called "wrap-around sleeves" have been developed for such applications. Essentially these are slit heat-recoverable sleeves made of a material which can be wrapped around the backing to form a generally tubular shape and which are provided with means for retention in the wrapped condition during recovery. Various types of heat-resilient wrap-around sleeves have already been described, e.g. in US-PS 3,379,218, GB-PS 1,155,470, 1,211,988 and 1,346,479 and the German patent applications P 26 00 647.3, P 26 35 001.6 and P 25 43 358.3.

Such heat-resilient wrap-around sleeves have proven extremely successful in numerous applications. However, although it was proposed, for example in GB-PS 1,155,470, to use them in the form of so-called 90 ° tubular shoes or protective caps, it was not possible to obtain the tight, wrinkle-free fit over bends or curves that the customer had is desired and which is usually an essential requirement for proper closure of, for example, a joint or leak in such a bend. There remains a need, therefore, for a wrap that is suitable for use in sealing, bonding, isolating, and / or generally protecting substrates in non-linear layers.

The invention is based on the knowledge that a heat-resilient wrapping can suitably be formed from a heat-resilient plate-shaped material and that by suitable selection of the shape of such a plate material in its heat-resilient form, the wrapping resets itself tightly over a curvature while adapting to the curvature.

Therefore, in its broadest aspect, the invention relates to a heat-resilient wrap made of a plate-shaped material which is adapted to retract closely over a curvature in a base while adapting to this curvature and thereby substantially avoiding the formation of undesirable wrinkles the wrapping being provided with means to facilitate its attachment in the pre-recovery position.

Within its broad aspect, the invention further relates to a heat-restoring part adapted, either by itself or in conjunction with another similar part thereon, to be wrapped around a curve, which part comprises a sheet of heat-restoring material which is shaped so as to that it has at least one area of greater width (to accommodate the outer side of the curve) and at least one area of smaller width (to accommodate the inner side of the curve) and with means on or adjacent to at least one of its edges for the purpose of facilitating their fixing in position before resetting is provided.

The invention also relates to a method for producing such heat-resilient wrappings, which is characterized by the following stages:

(a) Deformation of a plate made of a suitable material with the formation of the named areas of greater and smaller width,

(b) Conversion of this plate into the heat-recoverable state and

(c) attaching fasteners to or adjacent to one of the edges of the panel, steps (a), (b) and (c) being able to be carried out in any order and, if desired, two or more of these steps being carried out simultaneously .

The heat recoverable articles according to the invention are typically used for bends of 30 ° or more, such as bends of 60 to 120 °, especially "right angle" bends of 80 to 100 °.

The heat-resilient wrap-around part according to the invention can be used solely for wrapping a curve. It can be formed, for example, with the formation of two outer areas of greater width, which are connected by a central area of smaller width. Such a part can be formed from a circular plate, for example by molding, e.g.

In use, such a part is positioned over a curve or bend so that its areas of greater width lie on the outer side of the curve and its area of lesser width lies on the inner side of the curve, with the edges lying on the outer curve of the item have been fastened together prior to restoration. A similar part can of course be made with a central area of greater width connecting two outer areas of smaller width, the fastening means being provided at the edges of the one or both outer areas and these edges being fastened together on the inner side of the curve prior to recovery.

In all preferred embodiments of the invention, the plate width decreases from the area of greater width to the area of smaller width.

According to a preferred embodiment of the invention, the wrapping is made from two heat-resilient parts which are fastened to one another at their edges before resetting. The two parts are preferably similar in shape and size and may, for example, be in the shape of a truncated triangle or, preferably, a truncated triangle

Sector with a longer, preferably convex edge and a shorter, preferably concave edge, the two longer and the two shorter edges are already attached to each other on the outer and inner curvature before the reset.

The fastening devices can consist, for example, of a contact adhesive or a heat-activated peroxide, which are applied as a coating to the surface of the heat-resilient object (if the entire wrapping consists of two parts, only one part needs to be coated in this way; the adhesive or the peroxide can, if desired, in some cases applied in place immediately prior to use). However, the fastening devices preferably have a profiled part on or in the vicinity of at least one edge of the heat-resilient object. Suitable fastening devices are described, for example, in the above patents and patent applications, the use of a fastening device of the rail-and-channel type, as in GB-PS 1.155.470 and German patent applications P 25 00 647.3, P 26 35 001.6 and P 25 40 358.3 described (in which, in a preferred embodiment, the profiled parts themselves are formed by heat recovery, are preferred.

The fastening devices are preferably provided in the areas of greater and lesser width, but this is not essential. For example, suitably shaped parts can be attached along the sides of the curve in place of the outer and / or inner curve of curvature. In this regard, the invention provides a wrap for a bend or curve made from one or more heat recoverable sheet-like members shaped and / or dimensioned to move adapt to the curvature. Thus, in one embodiment, the wrap is made by attaching a generally longer plate (which is wrapped around the outside of the curve) to a generally shorter plate (which is on the inside of the curve). In such an embodiment it is not necessary for one of the plates to have areas of greater and smaller width.

The heat-resilient wraparound parts according to the invention are advantageously provided on one surface (after that which touches the base in use) with means for sealing, for example a layer of an adhesive or a putty.

In a preferred embodiment of the method according to the invention, a sheet, for example made of crosslinked polyethylene, is stretched in the heated state in order to make it heat-recoverable and, after cooling, cut in the stretched state into the required shape. The stretching can take place in one direction, but in some cases stretching in more than one direction is advantageous, it being possible to bring the plate into the desired shape during the stretching. This eliminates the need for another cutting operation. The plate is advantageously provided with a profiled fastening device along at least one of its edges which can be used to grip the plate during stretching.

The term "width" as used herein means that dimension which, when the closure is positioned about the curve, is in the direction of the curve.

Various forms of the invention are illustrated by way of example with reference to the following drawings:

Figure 1 shows a plate of heat-restoring material suitable for use in accordance with the invention.

Figure 2 shows another form of plate suitable for the purposes of the invention.

Figure 3 is a cross section taken along lines 3-3 of Figures 1 and 2.

FIG. 4 shows a stretching device for use in the method according to the invention.

FIG. 5 shows in cross section the fastening mechanism used in the device of FIG.

FIG. 6 shows a heat-recoverable wrap-around part according to the invention.

FIG. 7 shows a wrap-around sleeve formed from two parts of the type shown in FIG.

Figure 8 shows the wrap-around sleeve of Figure 7 in position over a bend in a pad prior to recovery.

FIG. 9 shows the arrangement of FIG. 8 after resetting.

Figures 10, 10a and 10b illustrate a second form of heat recoverable member according to the invention.

FIG. 11 shows a third form of the heat-recoverable part.

In Figure 1, 1 is a rectangular plate made of cross-linked polyethylene, which profiled on its longitudinal edges 2 and 3

Has back 4 and 5.

FIG. 2 shows a similar plate depicted from a truncated section of a circle. This plate can be made by stretching the plate of Figure 1 in a suitable manner, thereby rendering it partially heat-recoverable. Alternatively, it can be brought into this shape, for example, by pressing or extrusion.

FIG. 3 shows the type and position of the profiled backs 4 and 5 more clearly.

FIG. 4 shows how the plate of either FIG. 1 or FIG. 2 can be stretched in order to make it heat-resilient according to the invention. The edges 2 and 3 of the plate 1 are firmly clamped in curved claws 6 and 7.

As clearly shown in Figure 5, the profile backs 4 and 5 are used to support the clamping. When the plate 1 has been brought into position and clamped within the jaws 6 and 7, the jaws are moved apart to stretch the plate as required, the stretching being carried out above the crystalline melting point of the crosslinked polyethylene.

The closure part 8 produced after cooling and, if necessary, after cutting is shown in FIG. It is clear here that the edge 2 has now become an area of greater width and the edge 3 has become an area of smaller width.

Figure 7 shows a wrap-around sleeve 9 which has been made by joining two parts of the type shown in Figure 6 at their shorter edges. The attachment 10 is not drawn in detail, but is generally made by using a channel-shaped part 11 in conjunction with the profile back 4 and 5 received.

Figure 8 shows the wrap-around sleeve of Figure 7 in position over a bend in the pad 12 with the longer edges of the parts secured together at 13.

FIG. 9 shows the position of the sleeve 9 around the base 12 after the heat recovery. It can be seen that the sleeve resets itself to form a closure which adapts to the curvature in the base and has no folds or other undesirable discontinuous areas. Such a closure can be used, for example, to connect two supports or for insulation, protection or repair of a single support.

In one embodiment described in connection with Figures 1 to 9, a heat-stable rectangular plate made of cross-linked polyethylene, which has a back along each of the two longitudinal edges and has a length of 62 cm and a width between the backs of 9.4 cm, is heated and expanded using the device of Figure 4 so that the width between the spines is increased to 30 cm. The plate is cooled to room temperature and then removed from the device. It is laid flat, after which two end pieces are cut off so that the length of the concave shorter edge is 30 cm. A similar procedure is repeated to produce a second part, whereupon the two parts are then assembled around a pipe bend as described in FIGS. 7 and 8. The spines in the two pieces are connected using a C-shaped metal trough that slides the length of the two pieces to hold them together.

The closure sleeve thus formed is heated so that it fits tightly around the bend of a pipe with a diameter of

17 cm around it shrinks. The pipe bend is such that the radius of the inner concave surface of the pipe is 5 cm and that of the outer convex surface of the pipe is 22 cm.

In FIG. 10 a further form of a closure part according to the invention is shown, two heat-resilient closure parts 14 and 15 having been fastened to one another at 16 and 17 along the line of curvature. To achieve the object of the invention, the part 14 lying on the inside of the curve is shorter than the part 15 lying on the outer side of the curve. The parts 14 and 15 can be used in a manner similar to that described above in connection with FIG 4, but preferably one of the claws 6 or 7 for making H- or O-shaped parts is reversed as shown in Figures 10a and 10b to function as outer and inner parts.

Finally, FIG. 11 shows a heat-resilient wrap-around part according to the invention which has been formed as a single piece from a heat-resilient plate. Such a part can be produced, for example, by expanding a circular blank of the sheet material and then cutting it to the final shape.

Claims (15)

1) Heat-resilient wrapping, characterized in that it is made of a plate-shaped material and resets itself over a curvature of the base in a tight fit to the curvature of the base while avoiding unwanted creases, the winding means to facilitate holding in place in front the provision. 2) Heat-resilient wrapping according to claim 1, characterized in that it is made from a single plate of a heat-resilient material which has means on or in the vicinity of at least one of its edges to facilitate retention in its position prior to recovery. 3) heat-resilient wrapping according to claim 1, characterized in that it has been made from at least two sheets of heat-resilient material, each of which is provided on or in the vicinity of at least one of its edges with means to facilitate retention in its position prior to resetting . 4) Heat-resilient wrapping according to claims 1 to 3, characterized in that the angle of curvature is 30 ° or more, preferably 60 to 120 ° and in particular 85 to 95 °. 5) heat-restoring part, characterized in that it can be wound tightly around a curvature alone or in conjunction with another similar part, this part consisting of a plate of a heat-restoring material, which under formation of at least one Area of greater width (to adapt to the outer side of the curvature) and at least one area of smaller width (to adapt to the inside of this curvature) has been deformed and in the vicinity of at least one of its edges with means to facilitate retention in place the provision is provided. 6) Heat-restoring part according to claim 5, characterized in that it is wrapped around the curvature and has two outer areas of greater width, which are formed by a central area of smaller width. 7) Heat-restoring part according to claim 6, characterized in that it has been formed from a circular plate and the area of the smaller width is in the vicinity of the center of the circle, while the areas of greater width are on the circumference. 8) heat-restoring part according to claim 5, characterized in that it is wrapped around the curvature and has two outer areas of smaller width, which are connected by a central area of greater width. 9) heat-restoring part according to claim 8, characterized in that it is formed from a circular plate and the area of greater width is in the vicinity of the center of the circle, while the areas of smaller width are in the peripheral areas. 10) heat-restoring part according to claim 7, characterized in that it cooperates with another similar part and has the shape of a truncated triangle with a longer and a shorter edge, at least one edge being provided with means for gripping the other similar part to form a tubular sleeve prior to recovery. 11) heat-restoring part according to claim 7, characterized in that it cooperates with another similar part and has the shape of a truncated circular segment, the peripheral edge and / or trimmed edge with means for gripping the other similar part to form a tubular sleeve before recovery having. 12) Heat-restoring part according to claim 12, characterized in that the peripheral edge is the longer edge and the cut shorter edge is concave. 13) Heat-restoring part according to claim 7, characterized in that the areas of larger and smaller width are not edge areas. 14) Heat-restoring part according to claims 7 to 14, characterized in that the angle of curvature is 30 ° or more, preferably 60 to 120 ° and in particular 80 to 100 °. 15) A method for the production of heat-resilient wrapping parts according to claim 7, characterized by the following stages: a) deformation of a plate made of suitable material with the formation of areas of greater and smaller width, b) Conversion of this plate into the heat-recoverable state and c) Missing this plate on or in the vicinity of a their edges with fastening devices, steps a), b) and c) being carried out in any order and two or more of these steps, if desired, carried out together.