GB2365095A

GB2365095A - Flexible protective sleeve

Info

Publication number: GB2365095A
Application number: GB0018594A
Authority: GB
Inventors: Alan William Atkinson; Carol Jayne Pindar
Original assignee: Federal Mogul Technology Ltd
Current assignee: Federal Mogul Technology Ltd
Priority date: 2000-07-29
Filing date: 2000-07-29
Publication date: 2002-02-13
Also published as: WO2002010633A1; GB0018594D0; AU2001277613A1; GB2365095A8

Abstract

A flexible protective sleeve 10 comprises a generally tubular wall 12 substantially enclosing a space 14 for containing an elongated member such as a bundle of wires or a pipe. The wall comprises a layer 22 formed from flexible sheet material having a density which is no more than 30% of the theoretical density of the material, the material also being resilient. The sleeve is manufactured by a method which comprises winding at least one strip 20 of said flexible sheet material of substantially constant thickness and width along the length of the strip into the shape of a helix of substantially constant diameter, the method also comprising fixing said strip in its helical form. Each strip winding 20 may abut the previous strip winding 20 (as shown) or may overlap (eg. figure 3).

Description

1 2365095 FLEXIBLE PROTECTIVE SLEEVE This invention is concerned with a

flexible protective sleeve.

Flexible protective sleeves are commonly used to protect elongated members, such as bundles of wires and pipes, in environments where abrasion, heat, corrosive materials etc may cause damage. Such sleeves are also used widely for reducing undesirable noise such as may be caused by vibration between wires or pipes and adjacent components. Such sleeves may also be used to bundle wires together for aesthetic reasons. Such sleeves are used in the engine compartments of vehicles driven by internal combustion engines. Such sleeves have a generally tubular wall substantially enclosing a space for containing an elongated member. Such sleeves need to be flexible enough to follow the bends in such wires or pipes. In other words, such sleeves need to be able to turn through relatively tight bends.

Some conventional flexible protective sleeves are in the form of convoluted tubes made of extruded plastics material. The convolutions enable the sleeve to bend without significant deformation with the convolutions moving apart on the outside of the bend and moving together on the inside of the bend.

Other conventional flexible protective sleeves are made by braiding, knitting or weaving together plastics monofilaments.

It is a disadvantage of the above-mentioned conventional methods of manufacturing flexible protective sleeves mentioned-above that they are not suitable for use with a range of materials which have properties which are desirable for many uses of flexible protective sleeves. Such materials include 2 low-density flexible materials, ie having a density no more than 50% of the theoretical density of the substance from which the material is made. Such low density flexible materials include felts and foams which are not suitable for braiding, weaving, or knitting. It is possible to form flexible protective sleeves from foam by foaming a tube as it is extruded or by cutting a tube from a block of foam but both these methods can require an undesirably thick tube wall.

It is an object of the present invention to provide a method of manufacturing a flexible protective sleeve in which low-density flexible materials can be used to give walls of appropriate thickness.

The invention provides a method of manufacturing a flexible protective sleeve comprising a generally tubular wall substantially enclosing a space for containing an elongated member such as a bundle of wires or a pipe, the wall comprising a layer formed from a flexible sheet material, the material having a density which is no more than 30% of the theoretical density of the substance from which the sheet material is formed, the sheet material also being resilient, wherein the method comprises winding at least one strip of said flexible sheet material of substantially constant thickness and width along the length of the strip into the shape of a helix of substantially constant diameter, the strip being at least 0Amm in thickness, the method also comprising fixing said strip in its helical form.

A method according to the invention enables a flexible protective sleeve to be easily manufactured, for example by winding the strip on to a mandrel.

Strip winding machinery which can be used for such winding is available commercially and is used to manufacture cardboard tubing. A flexible protective sleeve manufactured by a method according to the invention can have good cushioning and impact properties, preventing rattling, and good thermal insulation properties. Where the strip is made from foam, eg polyurethane or melamine formaldehyde, the wall can have a reduced thickness as compared with established tubes made from foam. The strip may 3 also be made from fibres of polymeric materials, eg polyester, natural materials, ceramics, glass or minerals.

Preferably, in a method according to the invention, the strip is at least 0.8 mm in thickness.

Where said layer is formed by a single strip and the pitch of said helix is substantially equal to the width of said strip, measured in the longitudinal direction of the sleeve, so that successive turns of said helix abut one another, the flexible protective sleeve can have a substantially constant wall-thickness.

In this case, said strip may be fixed in its helical form by securing it, eg by adhesive, to a further layer of said wall, said further layer being formed from the same or different flexible sheet material. The further layer may be helically wound from strip with overlapping edges.

Said layer may, however, be formed by a single strip but the pitch of said helix may be less than the width of said strip, measured in the longitudinal direction of the sleeve, so that successive turns of said helix overlap one another. In the case, said strip may be fixed in its helical form by securing together overlapping portions of successive turns of said helix, eg by adhesive or stitching.

Said layer may be formed by two or more strips of similar material, each strip being wound into the shape of a similar helix, and each strip being located in the gap between successive turns of the other strip or strips, ie a multi-start helix is used.

Said strip may be fixed in its helical form by securing it to a further layer of said wall, said further layer being formed from flexible sheet material. Said further layer of said wall may be located either inside or outside the firstmentioned layer and may be formed from a strip wound into the shape of a helix. Said further layer may be formed from the same material as the first- 4 mentioned layer or from a different material. Said further layer may comprise a film of metal, eg an alloy of aluminium, which is a good reflector or infra-red radiation. For example, a metallised polymer film or aluminium foil may be used.

A sleeve according to the invention may also comprise one or more helices of soft metal wire or strip or of springy wire or of springy plastics strip, to assist in retaining the sleeve's shape.

A method according to the invention may also comprise forming a long itud ina lly-extend ing slit through said wall, thereby giving access to said space.

The invention also provides a flexible protective sleeve made by a method according to the invention, which preferably has a wall thickness of at least 0.5mm, preferably at least l mm, and the ratio of its wall thickness to its internal diameter greater than 0.05:1 but less than 0.5: 1.

There now follow detailed descriptions, to be read with reference to the accompanying drawings, of eight examples of methods of manufacturing a flexible protective sleeve which are illustrative of the invention.

In the drawings..

Figure 1 is a diagrammatic longitudinal cross-sectional view taken through a first illustrative sleeve manufactured according to the first illustrative example; and Figures 2 to 8 are diagrammatic cross-sectional views similar to Figure 1, but only showing one half of the section, taken through sleeves manufactured according to the second to eighth illustrative examples, respectively.

Example 1

Example 1 is a method of manufacturing a flexible protective sleeve 10 comprising a generally tubular wall 12 of circular transverse crosssection. The wall 12 substantially encloses a space 14 for containing an elongated member (not shown) such as a bundle of wires or a pipe.

In Example 1, a resilient polyester fibre felt (see Figure 1) with a thickness of 1.5mrn and a density of 140 kg1M3 was used (the theoretical density of polyester is approximately 1200 kg /M3. This felt was in the form of a strip 20 of constant thickness and constant width (40mm) along the length of the strip.

The strip 20 of felt was wound into the shape of a helix of constant diameter. Specifically, the strip was wound on to a mandrel of 25mm diameter so that each turn of the strip abutted its neighbours, ie the pitch of the helix was equal to the width of the strip, measured along the length of the sleeve. This gave a layer 22 of the wall 12, the layer 22 being formed from resilient flexible sheet material having a density less than 30% of the theoretical density of the material. In Figure 1 (and Figures 2, 4, 6 and 7), spaces are shown between the successive abutting turns of the strip 20, for clarity.

At the same time as the strip 20 was wound on to the mandrel, a strip 24 was helically wound on to the outer surface of the layer 22 to form a further layer 26 of the wall 12.overlying the layer 22. The strip 24 was formed from flexible sheet material which consisted of three overlying layers bonded together, these layers being a central support layer formed of polyester film 50mm wide and 50 microns in thickness, an inner layer formed of acrylic pressure-sensitive adhesive which secures the strip 24 to the strip 20, and an outer layer formed of a thin film of aluminium deposited on the polyester film. As the polyester film is bonded to the adhesive which adheres to the strip 20, the application of the layer 26 serves to fix the strip 20 in its helical form. The film of aluminium provides an infra-red reflective outer surface.

6 The strip 24 was 50mm wide so that successive turns of the strip 24 overlapped one another, ensuring a continuous outer surface of aluminium.

The sleeve 10 has good impact damping properties, and good thermal insulation properties.

Example 2

Example 2 is illustrated by Figure 2. In Example 2, the same felt strip 20 used in Example 1 was wound into the shape of a helix to form an inner layer 30 of the wall 31 of the second illustrative sleeve 32. Simultaneously, a further layer 34 of the wall 31 formed from a helically wound strip 36 was formed on top of the layer 30, and an outer layer 38 (which could be omitted) of the wall 31 formed from helically wound strip 40 (the same as the strip 24 in Examplel) was formed on top of the layer 34. The strip 36 forming the layer 34 consisted of a layer of the same felt which forms the strip 20 and a layer of adhesive 42 bonded to the felt. The adhesive 42, which (as shown in Figure 2) covers only part of the strip 36, adheres to the layer 30, thereby fixing the strip 20 in its helical form. The adhesive 42 may be in discrete patches, stripes running longitudinally of the sleeve 32, or stripes running circumferentially of the sleeve 32 Such stripes of adhesive may be eg 2mm wide and 0.5mm thick and spaced 2mm apart. Such strips may be interrupted to give discrete patches eg 5mm by 2mm.

Example 3

In Example 3 (see Figure 3), the wall 52 of the third illustrative sleeve 50 is formed from a single layer 54 formed from a single strip 56 wound into the shape of a helix. The strip 56 is wound at a pitch which is less than the width of the strip so that successive turns of the helix overlap one another. The strip 56 is formed from the same felt material as used in Example 1 except that it is formed with a step 58 to receive the overlapping portion of the next turn of the strip 56. The depth of the step 58 equals the thickness of the strip 56.

Adhesive (not shown) secures the overlapping portions of the strip 56 together, 7 thereby fixing the strip 56 in its helical form.

Example 4

The fourth illustrative sleeve 60 shown in Figure 4 was manufactured in the same way as the sleeve 50 of Example 3, the difference being that the wall 62 of the sleeve 60 is formed from a strip 64 which is formed with steps 66 along both edges. The steps 66 were formed by compressing the material of the strip 64 and holding at'the compressed thickness by impregnation with adhesive (an alternative being to heat the strip 64 to above its melting/softening temperature so that the fibres in the compressed portion stick together). The steps 66 have a depth which is half the thickness of the strip 64 and are arranged to receive overlapping stepped portions of the next turn of the strip 64 so that the inner and outer surfaces of the sleeve 60 are substantially cylindrical.

Example 5

In Example 5 (see Figure 5), the wall 72 of the fifth illustrative sleeve 70 is formed from an inner layer 74 formed from a single strip 76 wound into the shape of a helix, and an outer layer 78 formed from a single strip 80 also wound into the shape of a helix on top of the layer 74. In this case, the strips 76 and 80 are both formed of the same felt material used in Example 1 but are wound at a pitch which is greater than their width. This causes each layer 74 and 78 to have a helical gap 82 and 84, respectively, therein. However, the gaps 82 and 84 have a width which is less than the width of the strips 76 and 80 and the gaps are displaced longitudinally of the sleeve 70 so that the gap 82 is bridged by the strip 80 and the gap 84 is bridged by the strip 76. The strips 76 and 80 are adhered to one another along the edges of the gaps 82 and 84.

Example 6

The sixth illustrative sleeve 90 of Example 6 (see Figure 6) is the same as the sleeve 32 of Example 2 except that the outer layer 38 is replaced by a layer 92 which is similar to the layer 34.

Example 7

The seventh illustrative sleeve 100 shown in Figure 7 is a modification of the sleeve 10 of Example 1. In addition to the layers 22 and 26, the sleeve 100 has an inner layer 102 formed from the strip 24 and applied to the inner surface of the layer 22. This is achieved by winding the strip 24 on to the mandrel with the adhesive facing outwardly (the aluminium layer being omitted, if desired), and winding the strip 20 on top of the strip 24. This gives the space 14 a smoother surface.

Example 8

The eighth illustrative sleeve 110 (see Figure 8) is similar to the sleeve 10, having layers 22 and 26 made from strips 20 and 24, but also comprises three helices of wire 112, 114, 116 formed from wire with a thickness of 0.3mm. The three helices are wound at the same pitch as the strips 20 and 24 and are incorporated between the layers 22 and 26. The wire helices reduce "kinking" when the sleeve is bent and also increase crush-resistance.

The eighth sleeve 110 is manufactured by winding the strip 20 on to a mandrel, winding the three wire helices 112, 114, 116 on top of the strip 20 and winding the strip 24 on top of the wires forming the helices.

In modifications of Examples 1 to 8, the strips 20, 36, 56, 64, 76 and 80 are replaced by strips formed from a polyurethane foam with a thickness of 3.3mm and a density of 58 kg1M3 when uncompressed (the theoretical density of polyurethane is approximately 1100 kg1M3).

In modifications of Examples 1 to 8, the adhesive is applied to the strips 24, 36, 56, 64, and 76 or 80, as they are wound, eg by extruding or spraying adhesive on to the polyester support film of the strip 24 as it passes from a reel 9 to the mandrel. This simplifies the handling of the strip and allows solventbased or hot-melt adhesives to be used. Alternatively, the adhesive may be provided as pressure-sensitive adhesive on double-sided tape. For example, where heat resistance is required, the flexible sheet material may be made of glass fibre and may be secured by a refractory cement (eg a water-based colloidal silica). However, such cements take a long time to set and form a bond. When using these cements, it is possible to temporarily fix the helix in position using a fugitive hot melt adhesive or a pressure sensitive adhesive and, once the refractory cement has set permanently securing the helix in its helical form, the fugitive adhesive can be removed, eg by heating.

In modifications of Examples 1 to 8, instead of adhesive, stitching or welding may be used to attach the strips together or to attach overlapping portions of the same strip together.

Claims

1 A method of manufacturing a flexible protective sleeve comprising a generally tubular wall substantially enclosing a space for containing an elongated member such as a bundle of wires or a pipe, the wall comprising a layer formed from a flexible sheet material, the material having a density which is no more than 30% of the theoretical density of the substance from which the sheet material is formed, the sheet material also being resilient, wherein the method comprises winding at least one strip of said flexible sheet material of substantially constant thickness and width along the length of the strip into the shape of a helix of substantially constant diameter, the strip being at least 0Amm in thickness, the method also comprising fixing said strip in its helical form.

2 A method according to claim 1, wherein said layer is formed by a single strip and the pitch of said helix is substantially equal to the width of said strip so that successive turns of said helix abut one another. 3 A method according to claim 1, wherein said layer is formed by a single strip and the pitch of said helix is less than the width of said strip so that successive turns of said helix overlap one another. 4 A method according to claim 3, wherein said strip is fixed in its helical form by securing together overlapping portions of successive turns of said helix. 5 A method according to claim 1, wherein said layer is formed by two or more strips of similar material, each strip being wound into the shape of a similar helix, and. each strip being located in the gap between successive turns of the other strip or strips.

6 A method according to any one of claims 1 to 3 and 5, wherein said strip is fixed in its helical form by securing it to a further layer of said wall, said further layer being formed from flexible sheet material. 7 A method according to claim 6, wherein said strip is secured to said further layer by adhesive. 8 A method according to claim 7, wherein said adhesive is arranged in patches or stripes. 9 A method according to either one of claims 7 or 8, wherein the adhesive comprises a fugitive adhesive for temporarily holding the strip and a further adhesive for permanent bonding. 10 A method according to any one of claims 6 to 9, wherein said further layer is formed from a strip wound into the shape of a helix. 11 A method according to claim 10, wherein said further layer has overlapping edges.

12 A method according to either one of claims 10 and 11, wherein said further layer is formed from the same material as the first-mentioned layer. 13 A method according to either one of claims 10 and 11, wherein said further layer comprises a film of a metal which is a good reflector of infra-red radiation. 14 A method according to any one of claims 1 to 13, wherein the method also comprises incorporating in the sleeve one or more helices of soft metal wire or strip or of springy wire or of springy plastics strip, to assist in retaining the sleeves shape.

12 A method according to any one of claims 1 to 14, wherein the method also comprises forming a longitudinally-extending slit through said wall, thereby giving access to said space.

16 A method according to any one of claims 1 to 15, wherein the flexible sheet material is made from fibres of polyester, ceramic or glass, or from foam of polyurethane or melamine formaldehyde.

17 A method according to any one of claims 1 to 16, wherein the strip of flexible sheet material is at least 0.8mm in thickness.

18 A method according to any one of claims 1 to 17, wherein the wall thickness of the sleeve is at least 0.5mm and the ratio of its wall thickness to its internal diameter is greater than 0.05:1 but less than 0. 5A.

19 A method of manufacturing a flexible protective sleeve comprising a generally tubular wall substantially enclosing a space containing an elongated member such as a bundle of wires or a pipe substantially as hereinbefore described with reference to any of the accompanying drawings. 20 A flexible protective sleeve made by a method according to any one of claims 1 to 19.