Patent Publication Number: US-2012036910-A1

Title: winding apparatus for and method of manufacturing a helically wound tubular structures

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a United States national phase application under 35 U.S.C. §371 of International Patent Application No. PCT/GB2010/050057 filed on Jan. 14, 2010, and claims the benefit of Great Britain Patent Application No. 0900724.6 filed on Jan. 16, 2009, both of which are herein incorporated in their entirety by reference. The International Application was published as International Publication No. WO 2010/082061 on Jul. 22, 2010. 
     FIELD 
     The present invention relates to a winding apparatus and a method of manufacturing structures and relates particularly to the manufacture of pipes and longitudinal structures formed by winding strips of material, such as metal, Kevlar, plastic, glass fibre, composites of such materials or strips formed from layers comprising one or more of said materials in a helical relationship. Other structures such as storage vessels, towers and support structures may also benefit from features described herein. 
     BACKGROUND 
     Presently it is known to manufacture tubular structures by winding pre-formed metal strip onto a rotating mandrel such that the strip is deposited onto the mandrel in a self-overlapping manner. The strip is retained in place by mechanical deformation of an edge thereof such that it interlocks with an adjacent edge, thereby to retain the strip in place on the final structure. EP0335969 discloses an apparatus for forming a helically wound tubular structure formed from a flat strip of metal wound onto a mandrel. The flat strip is fed from one or other of a pair of supply spools mounted concentrically with the axis of the tubular structure to be made. A rotating winding head is used to wind the strip onto the mandrel and includes a plurality of powered forming rollers which impart an initial form to the cross section of the metal strip before it is passed to a final set of rollers that lay the strip onto the mandrel. An edge of the strip is then swaged over so that it becomes mechanically locked to the previous layer over which it is wound. This is a complex process. Also provided is a mechanism for ensuring the strip supply is maintained constant and this mechanism includes speed control of the forming rollers. The coaxial supply bobbins are fed from an external supply spool so as to maintain the supply thereof. A welding station is used to join one end of the strip material to another. 
     U.S. Pat. No. 4,738,008 discloses a winding apparatus for forming a non-rotating helix of metal strip having a rotating store of metal strip provided radially outward of a winding head and means for providing the store of material to the winding head which rotates at a different speed to the store of material. In this process it is necessary to stop the process when the strip material has been consumed and a fresh supply thereof is added before production can be commenced. This can be a very lengthy process. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an apparatus for and method of manufacturing tubular structures which reduces and possibly overcomes some of the problems associated with the prior art. 
     Accordingly, the present invention provides a winding apparatus comprising an inner faceplate rotatably mounted for rotation about a longitudinal axis X-X and having an output station thereon; and an outer faceplate radially outward of said inner faceplate; wherein said inner faceplate includes a plurality of inner strip supports at an outer diameter thereof and onto which, in operation, a supply of material may be wound, said outer faceplate includes a plurality of outer strip supports and in which said inner strip supports comprise rollers mounted for radial displacement relative to said faceplate and said outer supports comprise rollers mounted for radial displacement relative to said inner rollers, thereby to accommodate a variable diameter of strip material. Such an arrangement provides support for the inner diameter of strip material as it is consumed and thereby helps maintain the integrity of the material and the balance of the apparatus as it rotates. 
     The apparatus may further include a plurality of inner pivot arms pivotally connected at a first end to said inner portion and provided with an inner support roller at a second end thereof and may also includes a plurality of outer pivot arms pivotally connected at a first end to said outer portion and including an outer support roller at a second end thereof. 
     Preferably, said inner or outer pivot arms are curved along its length so as to allow them to nestle amongst each other when retracted. 
     Advantageously, said pivotal connection arms and associated rollers are axially displaced relative to each other along a longitudinal axis X of the apparatus. 
     Preferably, said apparatus includes a first driving mechanism for rotating the inner faceplate about longitudinal axis X-X and may also include a second drive mechanism for driving said outer faceplate about said longitudinal axis X-X. 
     Advantageously, the apparatus further includes a faceplate brake for preventing rotation of said outer faceplate relative to said inner faceplate. 
     Conveniently, the apparatus further includes a pair of feed/clamp rollers for receiving a supply of strip material to said apparatus and for guiding said strip towards said inner faceplate. 
     Preferably, said apparatus further includes a strip clamping and cutting station. 
     Advantageously, said inner faceplate further includes a central bore for receiving a supply of core material onto which strip supplied to said apparatus may be wound. 
     Preferably, said apparatus further includes a core supply mechanism for supplying a continuous or semi-continuous supply of core material to said apparatus. 
     According to another aspect of the present invention there is provided a method of forming a tubular article on an apparatus comprising an inner faceplate rotatably mounted for rotation about a longitudinal axis X-X and having an output station thereon; and an outer faceplate radially outward of said inner faceplate; wherein said inner faceplate includes a plurality of inner strip supports at an outer diameter thereof and onto which, in operation, a supply of material may be wound, said outer faceplate includes a plurality of outer strip supports and in which said inner supports comprise rollers mounted for radial displacement relative to said faceplate and said outer supports comprise rollers mounted for radial displacement relative to said inner rollers, thereby to accommodate a variable diameter of strip material, the method comprising the steps of: winding a supply of strip material between said inner and outer rollers; consuming material from an inner diameter of said supply; and re-filling said apparatus with strip material by connecting a fresh supply thereof to an otherwise free end of said part consumed strip and rotating said inner portion thereby to draw material onto said inner rollers. Such an arrangement provides for the speedy charging and refilling of the strip stock. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be more particularly described by way of example only with reference to the accompanying drawings in which: 
         FIGS. 1 to 3  are partial cross-sectional views of different types of tubular structure that may be formed by the apparatus described herein; 
         FIG. 4  is a schematic side elevation of an apparatus according to aspects of the present invention; 
         FIG. 5  is a cross-sectional view of the winding head according to one aspect of the present invention; 
         FIG. 6  is a front view of the forming head shown in  FIG. 5  and for reasons of clarity omits some features shown in  FIG. 5 ; 
         FIG. 7  is a detailed front view of the winding head taken in the direction of arrow A in  FIG. 5 ; 
         FIG. 8  is a partial plan view of the winding head taken in the direction of arrow P in  FIG. 7 ; and 
         FIGS. 9 to 11  are end views of the winding head and illustrate various stages in the operation thereof. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Referring now to  FIG. 1  of the drawings, a tubular body indicated generally at  10  forms a pipe for use in a pipe system such as a pipeline carrying hot fluids (which may also be under pressure). The tubular body may comprise an inner portion in the form of an inner hollow core  12  which may be formed by any one of a number of forming processes known to those skilled in the art and an outer casing discussed in detail later herein and which may also be load carrying. In the preferred process the inner pipe comprises a continuously formed core, as will also be discussed in detail later herein however, one may have a core made from a plurality of discrete lengths inter-engaged with each other so as to form a long length. The outer casing indicated generally at  14  is formed on the inner hollow core  12  by helically winding a strip  16  of material onto the outer surface  12   a  of the core  12  in abutting or self-overlapping fashion similar to the manner which is described in detail for the formation of a pipe on a mandrel in the specific descriptions of the applicants U.K. Patent No. 2,280,889 and U.S. Pat. No. 5,837,083. The strip may be wound under tension and may have one or more transverse cross-sectional steps  18  and  20  each of which is preferably of a depth corresponding to the thickness of the strip  16 . The steps  18 ,  20  are preferably preformed within the strip  16 , each extending from one end of the strip  16  to the other to facilitate an over-lapping centreless winding operation in which each convolution of the strip accommodates the overlapping portion of the next convolution. Whilst the strip may comprise any one of a number of materials such as a plastic, a composite material or indeed metal, it has been found that metal is particularly suitable in view of its generally high strength capability and ease of forming and joining as will be described later herein. Examples of suitable metals include steel, stainless steel, titanium and aluminium, some of which are particularly suitable due to their anti-corrosion capabilities. The internal surface  16   i  of the strip  16  and the outer surface of the pipe  12   a  may be secured together by a structural adhesive, as may the overlapping portions  16   a  of the strip. The use of an adhesive helps ensure that all individual components of the tubular member  10  strain at a similar rate. The application of the adhesive may be by any one of a number of means but one particularly suitable arrangement is discussed in detail later herein together with a number of other options. 
       FIG. 2  illustrates an alternative arrangement in which the flat strip  16  is formed such that step  28  divides the strip into longitudinal portions and is also provided with ridges  30  running longitudinally thereof. The ridges are shaped to produce an external ridge and an internal groove into which an external ridge of a previously deposited portion nestles during forming. 
       FIG. 3  illustrates a still further arrangement in which the strip comprises a simple flat strip wound in abutting relationship and provided in multiple layers which may be staggered as shown. 
     Referring now more particularly to  FIG. 4 , from which it will be seen that an apparatus  50  for manufacturing helically wound structures comprises: an optional pre-forming portion  52 , in which a core  54  is formed; a forming station, shown schematically at  56  and described in detail later herein; and a post forming section, shown generally at  58  and including a number of optional features discussed later. In one arrangement of the optional pre-forming portion  52  there is provided a store of flat strip material in the form of a roll of metal strip  60  and a plurality of feed rollers  62  which feed the strip to forming rollers  64  and  66  which in turn roll the edges of the strip together around a central mandrel  68  so as to form a tubular structure  54  having confronting edges abutting each other (not shown). A welding apparatus shown generally at  70  and including a welding head  72  is used to weld together the confronting edges in a manner well known in the art and therefore not described further herein. An alternative core forming process might comprise the manufacture of a plurality of discrete lengths of tubular structure, each of which are provided with inter-engaging features on confronting ends thereof such as to allow a plurality of said lengths to be assembled into a long section of core. When employing such a core arrangement one may replace the strip forming and welding arrangement with a suitable feed mechanism (not shown) for feeding a plurality of said discrete lengths into the forming station in a continuous manner. Once formed, the core of whatever description is fed into the forming station  56 , which is best seen with reference to  FIGS. 5 and 6 . Referring now once again to  FIG. 4 , an optional post forming section  58  may include such things as an optional drive mechanism  152  and adhesive curing heater  154 . 
     Referring now to the drawings in general but particularly  FIG. 5  which is a side elevation of the forming station  56  and comprises a faceplate  74  upon which are mounted a plurality of forming rollers  76  and a set of diameter defining rollers, shown generally at  78 . As shown, the forming rollers are profiled so as to form a cross-sectional form to the strip as best seen in  FIG. 1  or  2 . It will, however, be appreciated that the forming rollers could impart an alternative form to the strip or may, in some circumstances, be eliminated all together. When provided, the forming rollers are best provided as a plurality of confronting rollers (best seen in  FIG. 6 ) between which the strip  80  is sandwiched as it passes therebetween so as to impart the desired profile into the strip in a progressive manner, with each pair of rollers increasing the deformation of the strip until the final desired profile is formed. As shown, the forming rollers are each driven by means of a drive gear  82 , each of which is mounted for rotation about an axis on said faceplate and engages on one side with a forming roller and on another side with a sun gear  84  formed on a non rotating or driven portion  86 , which is described in detail later herein. As the faceplate  74  rotates in the direction of arrow D ( FIG. 6 ) rollers  76  and gears  82  rotate therewith but as the rollers are coupled to the sun gear  84  they are caused to rotate about their axes and drive the strip through the pinch formed between said confronting forming rollers  76 . As shown, the forming rollers  76  are each slightly staggered along longitudinal axis X and the axis of rotation of each roller varies in accordance with the spiral angle as the strip  80  passes from the supply thereof to the diameter defining rollers  78 . It will, however, be appreciated that a simpler non staggered arrangement may be used where there is sufficient room to shape the strip and then position it correctly before applying it to the diameter defining rollers  78 . It will also be appreciated that both the forming rollers and/or the diameter defining rollers may be driven by a servo system or motor shown schematically at  79 . 
     In order to ensure an even feed of strip material from a supply thereof it may be desirable to provide a supply thereof in the form of an annular stock supply shown generally at  88 . Advantageously this stock supply may be provided in a cassette or stock support  90  comprising a plurality of support rollers  92  positioned outside of said forming station and being circumferentially spaced around longitudinal axis X. Said support rollers  92  cooperate with a outer portion S 2  of the stock of strip material  88  and allows the stock to rotate in the direction of arrow D about axis X. The strip material  80  is removed from an inner diameter (S 1 ) of said stock thereof and fed via a first strip supply guide roller  94  mounted for rotation on said faceplate  74  about an axis angled relative thereto. In order to drive the faceplate  74  one may provide a motor  96  and gear drive  98  coupled to a ring gear  100  provided on a back plate  102  which is directly linked to face plate  74  via annular portion  104  through which portion  86  extends. Also shown in  FIGS. 5 and 6  are a plurality of inner strip supports in the form of a plurality of rollers  110  provided at an outer diameter of said inner faceplate  74 . The rollers of  FIG. 5  are rotationally mounted to the inner faceplate  74  by means of rolling pins  112  which are circumferentially spaced around the circumference thereof. The pins  112  themselves are mounted for rotation in corresponding holes shown at  114  and positioned towards the end of pivot arms  113 . Whilst the operation of these rollers will be described in more detail later herein, it will be appreciated that the rollers are each radially translatable and mounted to rotate about the axis of the pin and thus support or guide inner portion S 1  of the supply of strip material  88  as it is consumed from an inner diameter. 
     Referring now to  FIGS. 5 to 7 , it will be appreciated that the outer support rollers  92  are mounted in circumferentially spaced relationship around an outer faceplate  118  and the faceplate be provided with a drive mechanism shown generally at  120  in  FIG. 7 . The drive mechanism comprises a motor or servo mechanism  122  having a gear  124  which drives ring gear  126  which is coupled to outer faceplate  118  so as to drive said plate  118  and rollers  92  as and when desired. In operation the motor  122  drives gear  124  which turns  118  which drives the collective set of rollers  92  en mass in a clockwise or counter clockwise direction. The rollers  92  are supporting the outer diameter S 2  of the strip material  80  and, in turn, drive the outer diameter thereof in the direction of arrow D or E in  FIG. 6 . The outer rollers  92  are each connected to the outer faceplate  118  by means of pivot arms  128  similar to those provided in connection with the inner rollers  110 . The pivot arms  128  are each pivotally connected to outer faceplate  118  by means of pins  130 , best seen in  FIG. 5 . It will be appreciated from  FIG. 7  that arms  113  and  128  are each preferably curved or cantered so as to allow the arms to nestle against each other in a particularly compact manner. In addition to this curvature, the arms may also be curved, cantered or angled along axis X so as to allow the arms to sit in side-by-side relationship when nestled together. This arrangement is shown schematically in  FIG. 8  in which, for the purposes of clarity, just one arm is shown. It will be appreciated by those skilled in the art that other forms of drive mechanism could include motors  122   a  and  122   b  coupled directly or indirectly to rollers  92 ,  110  (best seen in  FIG. 5 ). 
     From  FIG. 7 , it will be appreciated that inner and outer arms  113 ,  128  are able to swing so as to allow their respective rollers  110  and  92  to move radially inwardly or outwardly as may be required. The motion is in an arch as shown by dotted line Ar and whilst this motion will cause a degree of circumferential displacement this is easily accommodated by the rollers rolling along the surface of S 1  or S 2  as required. The rollers in this arrangement are able to keep in supporting contact with the strip material throughout the depletion process keeping it as one coherent mass which will assist with the maintenance of balance as the faceplates rotate. The rollers may be provided with a friction surface such as a rubber coating (not shown) in order to facilitate gripping of the strip material when required. Actuators shown schematically at  213  and  228  are provided for moving arms  113  and  128  as and when necessary or desired. 
     The diameter defining roller arrangement seen generally at  78  which, between them, act to curve the strip material by plastically deforming it around one of the rollers such as to define the diameter of the exiting strip are not central to the present application and the reader&#39;s attention is drawn to the present applicant&#39;s patent application PCT/GB2006/050471 which describes this feature in detail. An optional adhesive applicator  132  may also be mounted on the faceplate  74  for rotation therewith. The applicator may take a number of forms for supplying adhesive to the strip after it has been formed and one particular arrangement is shown in which a storage cassette  134  is provided with a roll of adhesive strip  136 . The storage cassette  134  is mounted for rotation about a spindle  138  mounted on the faceplate  74  for rotation therewith such that, upon rotation of the faceplate, adhesive strip may be dispensed onto the surface of the strip  80  as it is lain down onto the core  54  ( FIG. 5 ). The strip of adhesive may be provided in the form of a strip having a backing (not shown) and this backing may be removed by backing removing means (not shown) prior to said adhesive being applied. 
     It will be appreciated from the cross-sectional view of  FIG. 5  that the faceplate  74  includes a central hole  140  for receiving a core or liner  54  onto which said strip material  80  may be wound so as to form a final structure  142 . The central hole may be provided with a central support trunion  86  having a hollow centre which defines said central aperture  140  for receiving said core or liner  54 . When provided, the trunion may be mounted within said central hole  140  by means of bearings  142 , such that said faceplate  74  can rotate about said trunion  86 . 
     Referring to the drawings in general, it will be appreciated that a tubular structure may be manufactured by causing the faceplate  74  to rotate. This action in turn will cause the strip material  80  to be drawn from the cassette, passed through forming rollers  76  and into diameter defining rollers  78  at which point the desired diameter is formed by appropriate positional control of the diameter defining rollers  78 . As the strip exits the diameter defining rollers it is directed towards the core  54  and wrapped therearound in a self overlapping or abutting relationship as shown in  FIGS. 1 to 3 . Before the strip is finally deposited onto the core it may be supplemented by an adhesive dispensed as a strip thereof from dispenser  130 . Continuous rotation of faceplate  74  will cause continuous deformation and deposition of the strip  80  and this process will continue so long as there is a supply of strip material within the cassette store. Once the strip material has been depleted it is necessary to transfer fresh material onto the apparatus from a supply station (not shown) and weld one end to the other before recommencing operations. It will also be appreciated that some forms of structure need not have a core and the above process may be undertaken without a core being supplied to the faceplate. In such an arrangement it may be necessary to provide a support to the initial portion of tubular structure formed but once an initial portion has been formed the structure will be self supporting as new layers are effectively deposited down on a stable multi layer structure. Indeed, one may well adopt such an arrangement when it is desirable to form a tapered structure for which one would find it difficult to produce a tapered inner core. Structures without cores are, therefore, within the scope of the present invention. In the production of such a tapered structure it is simply necessary to vary the degree of bending applied to the strip and this can be done by applying a variable force to the diameter defining rollers  78  so as to change the rolling radius as required. This process may be controlled by the computer shown schematically at  150  in accordance with a pre-determined control methodology. 
     Referring now briefly to  FIG. 7  which illustrates the inner support rollers in more detail, it will be appreciated that, whilst the location and support may take any one of a number of forms, the arrangement of  FIG. 7  is particularly compact and allows the diameter of the structure to be kept to a minimum. The features of  FIG. 7  that might possibly not be appreciated from  FIG. 5  include the way in which arms and are spaced around the circumference thereof so as to provide substantially even support for the strip  88 . Additionally, it will be further appreciated that a compact design may be formed by placing the inner rollers on as small a diameter as possible whilst avoiding the arms  113  conflicting with the forming mechanisms. Still further, it will be appreciated that the strip  88  is fed from the inner diameter of the supply thereof and passes between two of said support rollers  110  as it is supplied to the first of the forming rollers  76 . One of said rollers may act as a guide roller to replace  94  as shown in  FIG. 6 . The primary function of the inner support rollers  110  is to provide a support mechanism onto which the strip material  88  may be wound and through which it may be dispensed to the winding head. Each roller  110  is mounted for rotation on a spindle  112  which is, in turn, mounted on the inner portion  102  via roller support arm  113 , best seen in  FIG. 7 . In operation the strip material may slide over rotating inner rollers  110  as it is supplied to the winding station. 
     It will be appreciated that whilst the inner rollers  110  and the faceplate  74  are shown in two different planes in  FIG. 5  they may be provided in the same plane. In such an arrangement the forming rollers  76  and diameter defining rollers  78  are simply provided at a diameter smaller than that of the support rollers  110 , as shown in  FIG. 7 .  FIGS. 9 to 11  illustrate a set of clamp/feed rollers  160  positioned at an outer diameter of the winding head, the function of which will be described later herein. 
     The various stages of the winding process and replenishment steps will now be more particularly described with reference to  FIGS. 9 to 11 . 
     In  FIG. 9  there will be seen a completely wound supply of strip material  88  which has been wound onto the winding head by rotating inner faceplate  74  (at and thereby drawing a length of strip material onto the inner rollers  110 ). One may clamp the strip material so as to prevent it being supplied to the forming rollers and simply complete the re-stocking thereof. In this mode, strip material is supplied to the forming station by rotating the inner faceplate such as to pull fresh material through rollers  110  and onto the partially depleted supply of strip material supported by the inner rollers. This process is continued until the space between the inner and outer rollers  110 ,  92  is filled, at which point the apparatus is ready to commence or re-commence pipe production. At this time, the rollers  92 ,  110  will be at their respective radial extremities. During the “winding on” process it is also possible to produce an amount of pipe as the required material is taken from an inner diameter of the coil of material  88  and new material is added to an outer diameter thereof. It will be appreciated that by virtue of the difference in diameters of the pipe and that of the inner support rollers material will be consumed by the forming station at a much lower rate than it will be added to the support rollers  110 .  FIG. 10  illustrates the next step in the process at which point several meters of strip material has been wound onto the former so as to produce a section of pipe and virtually all of material  88  has been removed from the inner diameter. During this process one of the inner support rollers  110  also acts as a guide roller as the strip material changes direction as it rolls thereover. As the strip material is consumed a gap opens up between the forming rollers and the bulk of the strip supply at S 2  and the inner rollers  110  have to move radially outwards in order to support the strip  88  which is now at a much larger diameter. Once the strip supply is almost depleted the apparatus is stopped and outer portion  118  is reversed such as to allow the otherwise free end  88   a  of the strip to be fed back through clamp/feed rollers  160  at which point it can be joined to a fresh supply thereof by, for example a simple welding process followed by a subsequent and optional grinding of the weld so as to make a smoother joint. The weld portion is shown schematically at  162  in  FIG. 11 . 
       FIG. 11  illustrates the commencement of a building step in which material is added to the inner rollers  110 . At this point both sets of rollers  92 ,  110  are moved radially inwardly to the position shown such as to allow new strip material to be added at an inner diameter rather than an outer diameter. One is able to transfer strip material from the fresh supply thereof to the inner rollers at whatever speed that one rotates inner faceplate  74 , which is done by actuating motor drive  96  of  FIG. 5 . Outer rollers  92  are progressively moved radially outwards as the diameter of the new strip material increases. It will be appreciated that by virtue of the difference in diameter of the pipe being formed and that of the inner rollers  110  onto which fresh material  88  is being wound that significantly more material will be added per revolution than will be consumed by the formation of a pipe. Consequently, pipe production may be maintained whilst replenishing the stock of strip material. Once a full charge of fresh strip material has been wound on the winding process is stopped and the otherwise fee end of the fresh strip is allowed to feed through rollers  160  and be encompassed by rollers  92 . At this point the recharging process is complete and the arrangement will look like that shown in  FIG. 9 . In some circumstances, it may be necessary to cut any unwanted fresh strip material off at the roller position and pass the new free end through said rollers. 
     Recommencement of the winding process simply requires for the continuation of the driving process in which faceplate  74  and the forming rollers are rotated about axis X so as to cause strip material to be drawn through the rollers and deposited onto the core. It will be appreciated that when used to produce a pipe having a self overlapping structure one need not provide a core as the pipe is, in effect, self supporting. 
     It will also be appreciated that the apparatus may be used on strips of other materials such as Kevlar, plastic, glass fibre, composites of such materials or strips formed from layers comprising one or more of said materials. Indeed the machine lends itself particularly to use with some of these materials as it is able to pre-tension the strip as it is wound onto the final form of the tubular structure being formed. When used with composite materials having a portion of metal in the strip provided either as a layer or as part of any woven form thereof, said metal will act to maintain a degree of rigidity in the strip that will assist with the location thereof on the rollers and in maintaining a final curvature. Materials such as glass-fibre or Kevlar may be reinforced by a resin or other such material in the manner well known to those skilled in the art and, therefore, not described further herein. Clearly, any such materials may simply be wound into the desired shape without needing to be provided with a cross-sectional profile as described earlier. 
     It will also be appreciated that the above described method and apparatus may be used to cover an already existing pipeline with an outer casing. In this arrangement the already existing pipeline forms a core and the machine simply rotates around the core and moves therealong so as to lay down the outer wrap of strip material onto the pipeline. Such an approach could be employed when one wishes to repair or strengthen an already existing pipeline. 
     Still further, it will be appreciated that if portion  86  ( FIG. 5 ) is driven then it may benefit from being separately supported for rotation in bearings  200  provided in a fixed structure  202  and further provided with a drive mechanism shown generally at  204  and including, for example, a motor  206 , driving gear  208  and driven gear  210 , the latter of which is provided on portion  86 . Preferably, the controller is also connected to the motor for control thereof and for this purpose one may also provide control line  212  shown generally in  FIG. 6 .