Method of producing a tube assembly

Abstract: A method of producing a tube assembly in which a plurality of tubes (11; 21) follow a common path over at least a portion of their lengths, comprises assembling straight lengths of tube in appropriate relationship relative to one another, binding the assembled tubes (11; 21) together over the portions that follow a common path so that they are clamped tightly together and then bending the assembled tubes (11; 21), as one, to the required configuration of the common path. The assembled tubes (11; 21) may be bound together by continuously wrapping, using for example a sleeve 12 of heat shrink material, or may be clipped together at spaced locations along the portions following the common path.

Description: The present invention relates to tube assemblies and in particular assemblies of a plurality of bent tubes, said tubes having a common path for at least a portion of their lengths. Hitherto, where assemblies of bent tubes have been required, for example to provide brake and fuel lines for motor vehicles, each tube has been bent individually to the required configuration. Where such tubes are intended to follow the same path, they have been clipped individually relative to one another, typically in a flat configuration, in order to avoid abrasion of one tube against another. As a consequence, the assembly of tubes have been rather bulky and because of tolerance variations in individually bent tubes, it was sometimes difficult to achieve the required interposition of the tubes. GB 1,160,508 discloses a method of manufacturing a flexible pipe bundle cable in which several copper pipes are stranded together, annealed and then coated with a plastics sheath. The flexibility of the pipe bundle allows it to be laid round relatively tight bends, the copper pipes are not however permanently deformed by bending. WO-82/03806 discloses a method of permanently bending assemblies of tubes. However the assembly of tubes may only be clamped together at one end prior to bending, although they may be clamped together along their common path during the bending operation, after the formation of each of a series of bends. The present invention provides a method of producing permanently bent assemblies of tubes, in which the assembly of tubes may be clamped together along their common lengths in a single operation, prior to bending. According to the present invention a method of producing a tube assembly including a plurality of tubes having a common path over at least a portion of their lengths, comprises; a. assembling a plurality of straight lengths of tube in appropriate relationship relative to one another into an assembly of straight lengths of tube; b. binding the assembly of tubes over the length that corresponds to the common path thereby clamping the tubes in juxtaposed relationship but slidable axially relative to one another; and c. permanently deforming the bound portion of the assembled tubes to the required configuration of the common path by bending using bending equipment. In the assembly formed in the manner described above the tubes will be held tightly together over their common path by the binding. The assembly will consequently be compact and will rigidly maintain its shape, thus avoiding the problem of abrasion of one tube against another. Moreover, as the tubes are bent together, all the tubes will accurately conform to the required configuration. In order to permit slippage between the tubes as they are bent, it is advantageous that they have relatively low friction surfaces. Coating of the tubes with, for example, plastics material or Terne metal may assist in this respect. Where the tubes are required to follow separate paths beyond the portion following the common path, the ends of the tubes may be bent individually or in sub-assemblies which are bound together where appropriate, after the main bound portion of the bundle of tubes has been bent to the required configuration. As the bundle of tubes is tightly clamped together over its common path, conventional bending methods and equipment may be used. Preferably the tubes will be bound together by wrapping continuously over their common path. A shrink wrapping material may be used for this purpose. This may conveniently be achieved by the use of heat shrinkable materials, preferably plastics for example irradiated Polyolefins. These will be applied to the appropriate length of the assembled tubes in the form of a sleeve, which upon application of heat will shrink to firmly encapsulate the tubes and clamp them in the appropriate relationship relative to one another. The sleeve may be of composite construction, having an internal layer of adhesive which will bond to the tubes to provide additional location thereof. Other methods of shrink wrapping may alternatively be used. The straight lengths of tube which are initially assembled together should be cut to their appropriate lengths prior to assembly. The straight lengths of tube must be assembled in appropriate relationship relative to one another, with respect to both their relative longitudinal positions and their relative transverse positions. Any tube end forms and fittings that are required, may also be provided before assembly. If required the tubes may also be given identification marks near their ends, by any suitable method, so that individual tubes can be clearly recognised after assembly. By using wrapping materials with good corrosion resistent properties, the wrapping may also serve to protect the tubes against corrosion. The wrapped portion of the assembly may be sealed by means of a suitable substance such as an epoxy resin, which may be injected into the gaps at the ends of the wrapped portion and allowed to harden to form a permanent plug between the tubes and between the tubes and the wrapping. When using heat shrink sleeving to wrap the bundle, a layer of hot melt adhesive, which melts at the temperatures used to shrink the sleeving may be provided around the end of the sleeving on its ID, so that when the sleeving is shrunk onto the bundle of tubes, the adhesive will melt and form a plug. A preformed core of hot melt adhesive may also be located between the tubes, so that upon melting it will fill the interstices between the tubes. Alternatively, each tube in the assembly may be located through a pair of soft elastomeric plugs which are positioned at the ends of the common path of the assembly, so that when that length of the assembly is wrapped, the plugs will be compressed and the elastomer will seal the gaps. Corrosion protection may be extended to individual portions of the assembly by wrapping the individual lengths of tube. These individual wrappings will preferably overlap with the wrapping over the common path of the assembly, so that they may also be sealed with respect thereto. According to a further alternative, end sleeves of shrinkable material with integral fingers for the individual tubes or sub-assemblies of tubes may be applied at each end of the wrapped portion, these end sleeves being shrunk down onto the wrapped portion and individual tubes to provide the necessary seal therebetween. These end sleeves will preferably be applied before the ends of the tubes are bent to their individual paths. The fingers of the end sleeves may be extended or supplemented to provide complete coverage of the individual portions of the tubes. While it is advantageous to bind the tubes together by wrapping continuously along the whole length of the common path, the tubes may alternatively be bound together at spaced intervals by means, for example, of plastic cable ties or clips, screw clips such as "Jubilee" clips or short lengths of heat shrink sleeving. Such assemblies will permit the bending of the common lengths of the tube together, but will not provide improved corrosion properties. The invention is now described with reference to the accompanying drawings in which:- Figure 1 shows a tube assembly formed in accordance with the present invention; Figure 2 shows a section, on an enlarged scale, along the line II-II in Figure 1; and Figure 3 shows an alternative tube assembly formed in accordance with the present invention. In the tube assembly illustrated in Figure 1, four lengths of tube 11 are bound along their lengths which form a common path, by means of a length of heat shrink sleeve 12. One end of the heat shrink sleeve 12 is sealed by means of a heat shrink end cap 13 having integral fingers 14 for each of the individual tubes 11. The other end is sealed with a hot melt adhesive plug 15 which fills the gaps between the tubes 11, and between the tubes 11 and the sleeve 12. The length of the assembly covered by the sleeve 12 is thereby sealed to provide corrosion protection of the lengths of tube 11 enclosed therein. The heat shrink sleeve 12 and end cap 13 are placed over the tubes 11 before bending and are shrunk onto the tubes 11 to tightly clamp them together. Adhesive plug 15 is provided by a layer of hot melt adhesive on the internal diameter at the end of the sleeve 12 and by a core which is placed between the tubes 11. On heating the assembly to shrink the sleeve 12, the adhesive melts to fill the gaps and produce the plug 15. The tubes 11 are then bent, as one, over the common length defined by the sleeve 12 and individually along their portions extending beyond the sleeve 12. In the alternative embodiment illustrated in Figure 3, the lengths of tube 21 are bound tightly together before bending, by means of a series of plastic ratchet clips 22 positioned at spaced locations along the lengths of tubes 21 which follow a common path. The tubes 21 are then bent, as one, along the length defining the common path and individually at the ends. Additional clips 23 are provided for attachment of the tube assembly to, for example, a vehicle. The clips 23 may be applied prior to bending and serve to clamp the tubes 21 together or may be applied after the tubes have been bent.

Claims: A method of producing a tube assembly including a plurality of tubes having a common path over at least a portion of their lengths, characterised by the following steps; a. assembling a plurality of straight lengths (11; 21) of tube in appropriate relationship relative to one another into an assembly of straight lengths of tube; b. binding the assembly of tubes (11; 21) over the length that corresponds to the common path thereby clamping the tubes (11; 21) in juxtaposed relationship but slidable axially relative to one another; and c. permanently deforming the bound portion of the assembled tubes (11; 21) to the required configuration of the common path by bending using bending equipment. A method according to Claim 1 characterised in that portions of the tubes (11; 21) or sub-assemblies of the tubes (11; 21), beyond the portion of the assembly which follows a common path, are subsequently bent individually to follow separate paths. A method according to Claim 1 or 2 characterised in that the assembled tubes (11) are bound together by wrapping continuously along their common paths. A method according to Claim 3 characterised in that the assembled tubes (11) are wrapped with a heat shrinkable material. A method according to Claim 4 characterised in that a sleeve (12) of heat shrinkable material is applied to the appropriate length of the assembled tubes (11), the sleeve (12) being heated so that it shrinks to firmly encapsulate the assembled tubes (11) and clamp them in the appropriate relationship to one another. A method according to any one of Claims 3 to 5 characterised in that the wrapped portion of the assembly is sealed. A method according to Claim 6 characterised in that the gaps betwen the tubes (11) and between the tubes (11) and the wrapping are plugged by a suitable packing material. A method according to claim 6 characterised in that end sleeves (13) of shrinkable material with integral fingers (14) for the individual tubes (11) or sub-assemblies of tubes (11) are applied to each end of the wrapped portion of the assembly and are shrunk down onto the wrapped portion and individual tubes (11) or sub-assemblies of tubes (11), to provide a seal therebetween. A method according to Claim 1 or 2 characterised in that the assembled tubes (2) are bound together by binding at spaced intervals along their common paths.

Inventors: COOPER ANTHONY GERALD, EVANS STEPHEN JAMES, HARVEY DAVID CHARLES, COOPER, ANTHONY GERALD, EVANS, STEPHEN JAMES, HARVEY, DAVID CHARLES
Applicants: BUNDY TELFORD LTD, BUNDY (TELFORD) LIMITED
Application year: 1987
Main classification: F16L9
IPC codes: B21D7, F16L9