Patent Publication Number: US-2012042705-A1

Title: Apparatus for and method of manufacturing a helically wound tubular structure

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/GB2010/050055 filed on Jan. 14, 2010, and claims the benefit of Great Britain Patent Application No. 0900722.0 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 2010/082059 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 strip supports at an outer diameter thereof and onto which, in operation, a supply of material may be wound, and wherein said strip supports are radially adjustable thereby to accommodate a change in diameter of any supply of any material supplied thereto. Such an arrangement allows for the supply of strip material from an inner diameter thereof whilst also preventing a gap appearing between the supply of material and the inner supports and thus reduces and possibly eliminates unbalanced forces that might be created by unsupported strip material as it rotates about axis X. 
     Preferably, the supports comprise a plurality of rollers mounted for radial adjustment within radially extending slots within said outer faceplate. 
     Advantageously, one or more of said rollers may be mounted for rotation about a longitudinal axis at a first end of a pivot arm the otherwise free end of which is pivotally mounted to said inner faceplate. 
     Preferably, said apparatus further includes a plurality of second strip supports at an outer diameter of said outer faceplate. 
     Advantageously, said apparatus further includes a strip driving mechanism for rotating a supply of strip material supplied to said apparatus about said longitudinal axis X-X. 
     Preferably, said strip driving mechanism comprises a plurality of driven rollers at an outer diameter of said second faceplate which, in operation, engage with an outer diameter of a supply of strip material supplied to said apparatus. Said driven rollers may also comprise the second strip supports. 
     Advantageously, the apparatus further includes a strip brake for preventing rotation of an outer diameter of any strip material supplied to said apparatus relative to said faceplate. Said brake may comprise a friction brake. 
     Preferably, said brake comprises a driven roller having a brake system. 
     Advantageously, said apparatus further includes a pair of feed rollers mounted on an outer diameter of said outer faceplate for receiving a supply of strip material to said apparatus and for guiding said strip towards said inner faceplate. The apparatus may also include a strip clamping and cutting station. Said feed rollers may also form a strip clamp. 
     Preferably, 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. 
     Advantageously, said apparatus further includes a core supply mechanism for supplying a continuous or semi-continuous supply of core material to said apparatus. 
    
    
     
       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 ; 
         FIGS. 8 to 14  are end views of the winding head and illustrate various stages in the operation thereof; and 
         FIG. 15  illustrates one possible alterative form of the inner support rollers and their mounting on the inner faceplate. 
     
    
    
     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 aluminum, 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   o  may be secured together by a structural adhesive, as may the overlapping portions 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 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. 5 ) 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 rotating or non rotating portion  86 , which is described in detail later herein. As the faceplate  74  rotates in the direction of arrow D ( FIG. 6 ) gears  76  and  82  rotate therewith but as they are coupled to the sun gear  84  they are caused to rotate about their axes and drive the strip through the pinch formed between confronting forming rollers  76 . As shown, the forming rollers 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 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 stock supply  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 portion 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 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 non rotating 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 pivotally mounted to the inner faceplate  74  by means of pivot arms  112  which are circumferentially spaced around the circumference thereof and pivotally mounted thereto by means of pin arrangements shown at  114 . Whilst the operation of these rollers will be described in more detail later herein, it will be appreciated that the rollers are allowed to move out radially by pivoting about pins  114  and thus continue supporting the supply of strip material  88  as it is consumed from an inner diameter. An actuator shown schematically at  116  may be provided to move the rollers  110  outwardly. Alternatively, they may be urged outwardly by way of springs or another such mechanism (not shown). Referring now once again to  FIG. 5  from which it will be appreciated that the outer support rollers  92  are mounted in circumferentially spaced relationship around an outer faceplate  118  and may be provided with a drive mechanism shown generally at  120  in  FIG. 6  and seen in part in  FIG. 5 . The drive mechanism comprises a motor or servo mechanism  122  having a gear  124  which drives ring gear  126  which is coupled to the outer support rollers so as to drive said rollers as and when desired. Other forms of drive mechanism will present themselves to those skilled in the art and include but are not limited to direct drive mechanisms such as individual motors and possibly a collective drive mechanism employing a chain drive, neither of which are shown. In operation the motor  122  drives gear  124  which turns  126  which drives rollers  92  which in turn drive the outer diameter of the strip material in the direction of arrow D in  FIG. 6 . 
     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  130  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  132  ( FIG. 6 ) is provided with a roll of adhesive strip  134 . The storage cassette  132  is mounted for rotation about a spindle  136  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  114  by means of bearings  142 , such that said faceplate  74  can rotate about said trunion  86 . 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 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 and around inner rollers  110  and to forming rollers  76  before being passed into diameter defining rollers  78  at which point the desired diameter is formed by appropriate positional control of the forming rollers. 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. This process is described in detail later herein. 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. Structures without cores are, therefore, within the scope of the present invention. 
     Referring now briefly to  FIG. 7  which illustrates the inner support rollers in more detail, it will be appreciated that, whilst the supports and the mechanism associated with their radial movement 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 the rollers may nestle in optional cutouts  150  provided around the circumference of portion  102  and the way the pivot arms  112  may be curved or profiled to reflect that of the outer diameter at which they lie when retracted (as shown). Straight arms  112  are a suitable alternative. The arc subscribed by the deployment of the rollers is illustrated by arrows D having their center of radius at pivot point  114 . 
     It will be appreciated that whilst the inner rollers  110  and the faceplate 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. 8 to 14  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. 
     Also shown schematically in  FIG. 5  is a locking arrangement  170  comprising an actuator  172 , bolt  174  and corresponding hole  176  provided on the outer portion  118  and best seen in  FIG. 5 . This may be replaced or supplemented by stopping motor  120  and preventing it rotating, thereby to prevent rollers  92  from rotating which will, in turn, prevent S 2  rotating. 
     The various stages of the winding process and replenishment steps will now be more particularly described with reference to  FIGS. 8 to 14 . 
     In  FIG. 8  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  and thereby drawing a length of strip material onto the inner rollers  110 . This “winding on” process is continued until the space between the inner and outer rollers is filled, at which point the apparatus is ready to commence pipe production. During the winding on process an amount of pipe may be produced as the supply of strip material therefore is taken from an inner diameter of the coil of material  88 . It will be appreciated that by virtue of the difference in diameters of the pipe and that upon which the inner support rollers any material being supplied to the winding head will be supplied at a faster rate than it is being consumed and, consequently, one is able to add stock whilst producing a pipe. Alternatively, one may clamp the strip material so as to prevent it being supplied to the forming rollers and simply complete the re-stocking thereof by rotating the winding head and winding a fresh supply thereonto. 
       FIG. 9  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. Once the rollers have reached a desired outer diameter the strip material is driven to a convenient stopping position by driven rollers  92  and motor  120  before being reversed so as to allow the free end of strip  80   a  to be taken back into clamp rollers  160  where it is clamped in position in preparation for the next step of joining a new piece of strip material thereto. At this point rollers  110  are retracted, as shown, and create a space between themselves and an inner diameter of the outer portion S 2  of strip material. 
       FIG. 10  illustrates a new length of strip material  80   b  being welded to the otherwise free end  80   a  of strip  80  before clamp rollers  160 . At this point the outer diameter of the stock of material  88  is stationary and the inner winding head is still in motion such as to produce a pipe and to draw a supply of strip material from S 2  onto the inner rollers  110  where it forms portion S 1 . This process is shown part completed in  FIG. 11  and wholly almost completed in  FIG. 12 . The production process may continue whilst the new strip is welded onto the old strip and finished by, for example, grinding down the weld. 
       FIG. 13  illustrates the next step of the process at which point clamp  160  is released and a fresh supply of material is drawn from the source thereof. 
       FIGS. 13 to 14  illustrates the refreshing step in which new strip material continues to be supplied to the outer diameter of the stock thereof until the gap between it and the outer rollers  92  has been filled. At this point the supply of strip material may be stopped, the strip is cut at clamp  160  and the new free end  80   a  is allowed to pass through clamp rollers  160  such that it is free to rotate with the stock of material  88 , as shown in  FIG. 8 . Alternatively, the joining step may be completed quickly whilst the process continues. The above sequence of steps is repeated as often as necessary until the desired length of pipe has been produced. 
       FIG. 15  illustrates an alternative form of inner roller arrangement in which the rollers  110  are mounted for radial displacement in radially extending slots  180  provided on an inner portion  102  of larger diameter than that shown in  FIG. 5 . One of the advantages of this arrangement resides in the possibility of allowing the rollers  92  to move to a larger diameter than might be possible with the arrangement of  FIG. 5  before replenishment of the strip is necessary. This will have a positive impact on the number of times a replenishment exercise must be conducted before a given length of pipe is produced. 
     Additional features of this machine include feedback control from the computer to ensure the product diameter is maintained within desired limits and/or altered according to desired parameters. It will be appreciated that as one can control the degree of plastic deformation of the strip as it passes through the radius forming rollers  78  one can also control the final diameter of any tubular structure formed by this apparatus. 
     It will be appreciated that the described arrangement ensures an even supply of material. It also forms a complex interlocking profile in the material and winds the material onto a core at predetermined curvature, thereby providing a robust structure in the final windings as well as a suitable tensile compression. 
     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 herein. 
     Additionally, this arrangement advantageously provides a means of continuous or near continuous supply of winding material. Downtime for reloading of the apparatus with new stock is reduced, thereby also facilitating greater uniformity of the helical winding produced. 
     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 .