WO2014201506A1

WO2014201506A1 - A winding and welding machine

Info

Publication number: WO2014201506A1
Application number: PCT/AU2014/000640
Authority: WO
Inventors: Paul CENTOFANTI; Roy Duncan; Bernard RALSTON
Original assignee: Sekisui Rib Loc Australia Pty Ltd
Priority date: 2013-06-21
Filing date: 2014-06-20
Publication date: 2014-12-24

Abstract

A winding and welding machine tor lining an underground conduit with a helically wound pipe having and extruding assembly is disclosed. The machine includes: a drive assembly mounted to a frame for driving a strip into a strip path in a winding direction so as to present an incoming first edge to an adjacent second edge of a wound convolution of the strip and an extruding assembly mounted to the drive assembly or the frame. The extruding assembly includes an extruder. The extruder includes: a screw having a feed throat, and a welding rod pelletising assembly including a pellettiser for delivering pelletised plastic to the feed throat. The extruder includes a delivery nozzle mounted a barrel. An air heating assembly including a hot air delivery conduit having an annular exit formed in part by the delivery nozzle of the extruder is also disclosed.

Description

A WINDING AND WELDING MACHINE

PRIORITY DOCUMENTS

[0001] The present application claims priority from: Australian Provisional Patent Application

No.2013902279 titled "A Winding and Welding Machine" and filed on 21 June 2013, The content of this applications is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0001] The present invention relates to helically wound pipes. In a particular form, the present invention relates to apparatus and methods for producing plastic welded pipes within underground conduits.

BACKGROUND

[0002] Many techniques are currently known and used for relining underground conduits. One method involves placing a pipe winding machine in an access pit and then feeding an elongate plastic strip into the pit. The machine then winds the strip into an elongate helical pipe as it is fed down into the pit. The applicant has developed various machines and methods for winding such a helical pipe. Some of these methods do not require "over pumping" and can be earned out while a conduit being reiined is in service,.

[0003] In some applications, it is desirable to provide a fully welded pipe. Fully welded, or continuously welded pipes, are watertight. With helically wound pipes, the weld is very long and hence welding speed is important.

[0004] Existing machines and methods for winding and welding pipes underground produce welded joints rapidl and are able to produce a consistent weld, but are complex, bulky and difficult to set up.: They also require -significant time to set up and cannot easily be shut down and restarted.

[0005] There is thus a need to provide an improved method and apparatus that addresses o ameliorates the aforementioned problems or at least offers a useful choice.

SUMMARY

[0006| According to a first aspect of the invention, there is provided a winding and welding machine for lining an underground conduit with a helically wound pipe., the machine including:

an annular frame; a strip guide disposed around and supported by the annular frame, the guide arranged to guide a strip around a strip path when the machine is in use;

a drive asserably mounted to the frame for driving the strip into the strip path in a winding direction so as to present an incoming first edge to an adj cent second edge of a wound convolution of the strip; and

an extruding assembly mounted to the drive assembly or the frame, the extruding assembly including an extruder, the extruder including:

a screw having a feed throat; and

a welding rod pelletising assembly including a pelletiser for delivering pelletised plastic to the feed throat,

wherein, in use, the extruding assembly deli ers a molten bead for welding the first and adjacent second edges of the strip.

(0007] In one form the extruder includes;

a barrel, the barrel having a proximal end and a distal end;

a delivery nozzle mounted to the proximal end of the barrel, the delivery nozzle shaped and positioned to deliver a molten bead of plastic onto the incoming first edge of the strip; and.

a barrel heater assembly disposed around the barrel.

[0008] In one form the barrel heater assembly is slidably removable from the proximal end of the barrel.

[0009] In one form the barrel heater assembly includes;

a thermally conductive barrel heater body, the barrel heater body defining a bore fo receiving the extruder barrel; and

a plurality of heaters disposed around the bore.

[0010] In one form the heaters include electrical resistive heatin elements.

[0011] In one form the barrel heater body includes a plurality of heater cavities disposed around the bore, each heater cavity containing at least one of the plurality of heaters .

[001 ] In one form each heater comprises a removable cartridge heater.

[00Ϊ3] I one form the heaters are encapsulated so as to prevent fluid ingress to the heating elements.

[00143 In one form the machine further includes an insulating sleeve disposed around the heater body, the sleeve including layers of mica. [0015] In one form the delivery nozzle has an internal bore extending from a distal end threadahly connected to the proximal end of the barrel to a proximal end and wherein the internal bore tapers in a.

direction from the distal end towards the proximal end,

[0016] ^'In one form the machine fun her includes an air heating assembly, the air heating assembly including:

an electrical heating element;

a heat transfer element; and

a hot air delivery conduit having an annular exit formed in part by the delivery nozzle of the extruder.

[0017] in one form the heal transfer element comprises a thermally conductive air heater body, the air heater body shaped to form one or more helical air pathways around the electrical heating element.

(00l8| In one form the air heating assembly includes a pluralit of electrical heating elements, and wherein the air heater body is shaped to form one or more helical air pathways around each of the electrical heating elements.

[f)§19;j According to a second aspect of the invention, there is provided a winding and welding machine for lining an underground conduit with a helically wound pipe, the machine including:

an annular frame;

a strip guide disposed around and supported by the annular frame, the guide arranged to guide a strip around a strip path whe the machine is in use;

a drive assembly mounted to the frame for driving the strip downwards into the strip path hi a winding direction so as to present an incoming first edge to an adjacent second edge of a wound convolution of the strip;

a screw having a feed throat;

a welding rod pelletising assembly including a pelletiser for delivering pelletised plastic to the feed throat;

a barrel, the barrel having a proximal end and a distal end; and

a deli very nozzle mounted to the proximal end of the barrel, the delivery nozzle shaped and positioned to deliver a molten bead of plastic onto the incoming first edge of the strip;

an air heating assembl , the air heating assembly including a hot air delivery conduit having aa annular exit formed impart by the delivery nozzle of the extruder, [00:201 la one form the air heating assembly includes:

an electrical heating element; and

a heat transfer element.

[0021 J in one form the heat transfer eleraefit comprises a thermally conductive air heater body, the air heater body shaped to form one or more helical air pathways around the electrical heating element.

[00221 In one form, the air heater assembly includes a plurality of electrical hea ing elements, and wherein the air heater body is shaped to form one or more helical air pathways around each of the electrical heating elements.

[00231 According to a third aspect of the invention, there is provided a winding and welding machine for lining an underground conduit with a helically wound pipe:, the machine including:

an annular frame;

a strip guide disposed around and supported by the annular frame, the guide arranged to guide a strip around a strip path when the machine is in use;

a drive assembly mounted to the frame for driving the strip downwards into the strip path in a winding direction, so as to present an incoming first edge to an adjacent second edge of a wound convolution- of the strip;

an extruding assembly mounted to the dri ve assembly or the frame; and

a mount,

wherein the mount is positioned between the extruding assembly and the drive assembly.

{00241 In one form, the mount includes an interface assembly having:

a base connected to the drive assembly; and

a extrusion welding assembly frame, the extrusion welding assembly frame hingedly mounted to the base.

BRIEF DESCRIPTION OF DRAWINGS

|0025| Embodiments of the present invention will be discussed with reference to- the accompanying drawings wherein:

|0026| Figure I is a diagrammatic cross-sectional view of an underground conduit being relined using currently know apparatus and methods.

{0027] Figure 2 is a cross-sectional view of a plastic composite strip (profile) windable into a helical pipe. [0028] Figure 3 is a perspective view of a pipe wound from the plastic composite strip shown in Figure 2.

[00291 Figure 4 is a schematic cross-sectional view of an underground conduit being reiined using a machine according to the invention,

[0030] Figure 5 is a schematic cross-sectional view showing the apparatus of Figure 4 underground.

[0031] Figure 6 is a perspective view of an annular frame for guiding the strip into a helical pipe, the annular frame bein part of the apparatus shown in Figures 4 and 5.

[0032] Figure 7 is a diagrammatic close u perspective view of a portion of a winding and welding machine that accords with an embodiment of the invention.

[0033] Figures 8 A and 8B are isometric and exploded isometric views respectively of an extruder, which fo?ms a part of the winding and welding machine shown in Figure 7.

[0034] Figure 9 A is a front view of the extruding assembly shown in Figures 8 A and SB.

[0035] Figure 9B is a cross-sectional view taken through section lines 9B-9B, as indicated on Figure 9A.

[0036] Figure C is a close up view of a portion of the extruder shown in Figure 9B. as indicated by circle C.

[0037] Figure 9D is a rea view of a barrel heater assembly that forms part of the extruding assembly shown in Figures 8A and 8B.

[0038] Figure 9E is a cross-sectional view of the barrel heater assembly of Figure 9D, taken through section lines 9B-9B, as indicated on Figure 9 A,

[0039] Figure 9F is a cross-sectional view taken through section Sines 9F-9F, as indicated on Figure 9A.

[0040] Fi gures I OA and 1 OB are isometric and exploded isometric views respectively of an air heater, which forms a portion of the winding and welding machine, as shown in Figure 7,

[0041] Figure 1 1 is a cross-sectional view showing the extrusion welding assembly illustrated in Figure 7,

J0042] Figure 12 is an isometric view showin a portion of the dri ve tray extrusion weldin g interface assembly illustrated in Figure 7. [0043] Figure 13 is a similar isometric view to that of Figure 12 but in addition, shows the extrusion welding assembly frame that is illustrated in Figure 7,

[0044] Figures 14A and 14B are isometric and exploded isometric views respectively of an alternative air heater to that shown in Figures 10A and 1QB, which forms a portion of the winding and welding machine, as shown in Figure 7.

[0045] Figure 15 is a side view of (he alternative air heater shown in Figures 14 A and 14B,

[0046] Figure 16 A is a cross-sectional view of the alternative air heater shown in Figure 15 through section line 16A-16A.

[0047] Figure 16B is a cross-sectional view taken through section line 16B-16B, as indicated on Figure 16A.

DESCRIPTION OF EMBODIMENTS

[0048] Referring to Figure 1 , there is shown schematically in cross section an underground conduit 5 being relined usin an apparatus and method developed by the applicant. This apparatus and method utilises a winding machine 50 that includes an annular frame 60, sometimes referred to as a winding cage, and a drive assembly 80 in the form of a drive tray. Attached to the drive tray is an extruder that is ted with plastic pellets down a tube 82 from, a hopper 81 located up at ground level The extruder is heavy, requires significant start: up time and adds to the complexity of the inding machine 50. in order to operate the winding machine 50, care must be taken to ensure that the correct pellets are mixed, supplied and then delivered via the hopper 81 and the tube 82 io the extruder,

[0049] Turning no to Figures 2 and 3, Figure 2 shows a plastic strip 10 and its adjacent convolution 10' welded together by a bead 1 , The resultant wound and welded pipe 90 shown in Figure 1 is more clearly shown in Figure. 3.

[0050] Referring to Figure 4, a winding and welding machine 100 according to the invention is shown diagrainniaticaliy. This machine is shown in Figure 4 within an underground conduit 5 that is being relined. The machine 100 is positioned at the bottom of an access hole 3 and sits typically just above the base of the access hole 3. The machine 100 receives electric and hydraiilic power and compressed air from a power pack 95 located at ground level. The power pack 95, illustrated diagrammatically in Figure 4, includes a hydraulic pump 34, an air compressor 58 and an electrical supply 31 . A bundle of at least two hydraulic lines 35 feeds I hydraulic fluid to a hydraulic motor within the winding and welding machine I DO. Power supply cables 32 feed electrical power to the machine 100 and compressed airline 92 feeds compressed air to the machine 100.

[0651] Materials are also supplied from ground level to the machine 100 underground. A spool 101 feeds strip 12 to the machine 100 and a smaller welding rod sp ol 102 feeds a welding rod 103 to the machine 100, In other embodiments, not shown, the welding rod spool 102 may be located below ground level (for instance, within the access hole 3).

}0Θ52| As can be seen in Figures 4 and 6, the winding and welding machine 100 has an annular frame 110. The annular frame 110 may also be described as a winding cage. The winding cage 110 supports a strip guide, die strip guide comprising rollers 130, as is most clearly shown in Figure 6 (in other embodiments of the invention the strip guide may comprise low-friction guides other than rollers). The rollers are arranged to guide a strip 12 around a strip path when the machine is in use. The winding machine also includes a drive assembly in the form, of a drive tray 160 illustrated diagrammaticall in Figure 7. The drive tray 160 drives the strip 12 downwards into the strip path in a winding direction, so as to present an incoming first edge of the stri to an adj acent second edge of a wound convolution of the strip. This is illustrated more clearly in Figure 7.

[00S3] Turning now to the schematic cross-sectional view of Figure 5, the winding and welding machine is shown partially submerged within liquid 8 as it winds a pipe. The machine includes an annular frame, omitted from Figure 5 for clarity but shown in Figure 6 and a drive assembly mounted to the frame for driving the strip 12 downwards into the strip path. This is shown more clearly in Figure 7, Figures 5 and 7 show pinch rollers 71 and 72 of the drive assembly, or drive tray 160, The pinch rollers drive the strip into the strip path so as to present an incoming first edge 16 to an adjacent second edge 18 of a wound convolution of the strip 12. The machine 100 also includes an extruding assembly 300, as is illustrated in Figure 7. The extrudin assembly 300 is mounted to the drive tray 160, or alternatively, in other

embodiments of the invention, to the frame of the winding cage,

10054 Referring to. Figures 8 A and SB, it can be seen that the extruding assembly 300 includes an extruder 3:10 that is driven by a hydraulic motor 390. The hydraulic motor 390 is fed by hydraulic lines 392 and 394. Connectors 392' and 394' connect to hydraulic lines 35_» as previously described and illustrated in Figure 4. Alternatively,, a. manifold may be provided between the hydraulic lines 35 and the connectors 392' and 394'. The manifold may be mounted to the windin machine 100.

[00551 Turning now to Figure 8B, which is an exploded isometric view showing the extruding assembly 300 of Figure 8 A, it can be seen that the extruder 310 includes an extrusion screw 380. I0O56J The extruding assembly 300 includes a welding rod pelletising assembl 400. This pelletising assembly 400 is more clearly illustrated is Figures 9B and 9C. As cm be seen in Figure 9C, the welding rod pelietismg assembly 400 includes a welding rod feed screw 480 that feeds a welding rod into a peiietiser 455. The peiietiser 455 delivers pelletised plastic to the feed throat 381, as illustrated in .Figures 9^'C and 1 1 , f0057] A tube 164 connecting a welding rod spool stand 102' to the in-feed orifice or intake port 490 of the extruder may be provided. The purpose of the tube 104 is to provide a guide and/or a protected pathway for the welding rod 103 to be passed through. The tube 104 ensures that the welding rod 103 is kept free from contaminants such as soil or water, which could enter the extruding assembly 300 and cause damage. It also reduces the risk of impurities being mixed with the actual weld material reducing its strength. The tube 104 can be opaque or clear so as to provide the opportunit to view the welding rod 103 on its path to the extruding assembly 300. The tube can terminate before reaching the intake port 490 as shown in Figure 1 1, or alternatively may be joined to the intake port. In a further alternative- one or more pulleys may be provided to guide the welding rod 103 instead of providing a tube 104.

[00581 Figure 1 1 shows the welding rod 103 as it is pulled towards the peiietiser 455 by the welding rod feed screw 480.

10059} Referring again to the close up view of Figure 9C, it can be seen that from the feed throat 381 , the plastic pellets created by the peiietiser are engaged by the extrusion screw 380 of the extruder 310 and are drawn towards the proximal end 321 of the barrel 320.

[0660] The extruder 310 will now be described in more detail with reference to Figures 8A, SB, A, 9B, 9C, 9F and 1 1. The extruder 310 includes a barrel 320 that is most clearly shown in the eross-seetionai views of Figure 9B and 9F, The barrel 320 has a proximal end 321, having a male thread to which a delivery nozzle 330 attaches. As can be seen in the exploded view of Figure 8B_> fasteners 376' compress an end plate 376 against the distal end 322 of the barrel 320 and holds the barrel 320 against the welding rod pelletising assembly 400. The assembled condition is more clearly shown in Figure 9B.

[0061 J The deliver)' nozzle 330 has a female thread that threadably engages with the proximal end of the barrel 321. The delivery nozzle 330 has an internal bore 332 that extends from a distal end 333, which is threadably connected to the proximal end 321 of the: barrel 320, The internal bore 332 tapers in a direction from the distal end 333 to the proximal end 338 of the delivery nozzle 330. The applicant has found that the use of a tapered bore assists in providing and tuning the back pressure through to the exit 339 required for optimum operation of the extruder 310. As is illustrated diagrammaticaMy in Figure 5, it is necessary to have some length to the nozzle 330 so as to deliver the molten weld bead 19, as close as possible to the point at which: the edges 16 and 18 come together, as is shown in Figure 7. {0062] The internal diameter of the proximal end 338 of the delivery nozzle 330 is chosen to provide a molten bead 19, such as illustrated hi Figure 7, of an appropriate diameter and size. With previously known winding and welding machines of the type described above and illustrated in Figure 1 , that same proximal end iniemal diameter has continued tiirough the bore back towards the extruder. In other words, the diameter has remained constant, or in some cases has even been reduced due to bends in the nozzle. With the embodiments of the present, invention shown in Figure 7, and in particular with the provision of air ducting 600 that extends around the deliver)' nozzle 330, it has been found that a larger bore expanding back toward the extruder is able to be used. The hot air that flows completely around the delivery nozzle 330 ensures that the extradate is able to flow satisfactorily and remains heated as it passes tiirough the nozzle 330, The larger diameter greatly reduces the amount of pressure in the nozzle and back toward the extrusion screw 380. This improves the safety of the machine and simplifies operation.

[0063] Referring^'- to- Figures 9A, 9B and 9F, a barrel heater assembly 370 disposed around the barrel 320 is shown in detail. The barrel heater assembly 370 includes a thermally conductive barrel heater body 371 and the barrel heater body 371 defines a bore 379 for receiving the extruder barrel 320, Four heaters 374 are disposed around the bore 379 as is shown in Figures 9D and 9E, Figure 9F shows the extruder barrel 320 received within the bore 379 of the barrel heater body 371.

[Θ064] The heater assembly 370 i slidably removable from the proximal end 321 of the barrel 320. This is achieved easily after the nozzle 330 is unscrewed from the proximal end 321 of the barrel 320. This enables quick and easy replacement of a damaged heater assembly, The barrel heater assembly 370, separated from the barrel 320., is shown in Figures 9D and 9E.

|0β65] The heater assembly 370 includes electrical resisti ve heating elements and the heating elements are contained within a generally cylindrical heater enclosure, the enclosure being encapsulated so as to prevent fluid ingress to the heating elements. This is shown more clearly in Figures 9D and 9E. hi the embodiment shown in Figures 9A through to E, four electrical resistive heating elements in the form of barrel heater cartridges 374 are provided. The ends of the heater cartridges 374 are shown in Figure A. The cross- Sectional view in Figure 9E shows one pair 374 of barrel heater cartridges more clearly.

[00663 Referring to Figure 9A and Figure 9D, it can be seen that there are two pairs 374 of barrel heater cartridges and one barrel heater thermocouple 375 interposed between the cartridges of each pair. The thermocouples 375 enable a control system to accurately control the temperature of the barrel heater body }0067{ Again referring to Figure 9E, it can be seen thai the barrel heater assembly 370 defines a bore 379 for receiving the extruder barrel 320. Figures 9D and 9E also show the plurality (la this embodiment four) of heaters in the form of heater cartridges 374 disposed around the bore 379,

{0668} The heater 374 includes resistive heating elements that are supplied ith electricity throug cables 374' as is shown in Figure 9E,

(0069J Again referring to Figure 9B, it can be seen that the barrel heater body 370 includes a plurality of heater cavities 373 disposed around the bore 379. Each heater cavity 373 contains one of the heaters 374, in Figure 9B, only two of the four cavities 373 and heaters 374 are shown. Figure 9D shows the other two heaters 374 within further cavities 373.

10070] As should be clear from Figures 9 and 9E, the barrel hea ing assembly 370 is able to be

disassembled relatively easily. The barrel heater cartridges 374 can readily be removed for replacement or servicing.

[0071] When, fully assembled, the heaters are encapsulated so as to prevent .fluid ingress to the heating elements. This assists in. reducing any danger that may be posed by hot elements.

[0072] Again referring to Figure 9B. it can be seen that surrounding the heater assembly 370 is an insulating sleeve 377. The insulating sleeve 377 is advantageously made from layers of mica. Mica has an extremely low coefficient of thermal transfer and very effectively insulates the heater assembly. Surrounding the insulating sleeve 37 is an outer layer 378. The outer layer 378 ma be made from brass, plastic, silicone or other materials.

[0073] Referring again to Figure 7, it can be seen that adjacent to the extruding assembly 300 is an air heating assembly 500. The two components 300 and 500 together form an extrusion welding assembly 200. The air heating assembly 500 receives compressed-air from the air compressor 58, as shown

diagraniniatteally in Figure 4, via air line 92. Figure 1 OA shows the air inlet 521 to which the air hose 92 is connected. Figures 10A and 1 OB show electrical cables 512 that feed an electrical resistance heater that heats air entering through air inlet 521 and exi ting from air duct outlet 650.

[0074] The air heating assembly 500 is seen in more detail in the cross-sectional- view of Figure 1 1. As Figure 1 1 shows, cables 512 feed an air heater core 510. Within the air heater core 510 are electrical heating elements that transfer heat outwards to a heat transfer elemen 520. Air passes over the heat transfer element 520 before being delivered via sir ducting 600 to air duet outlet 650. As is clear from Figure 11 , the air exits at an annular exit formed in part by the deli very nozzle 330 of the extruder. [0075J Again- referring to Figure 7, delivery of a molten bead 19 for welding the first and adjacent second edges of the strip 16, 1 8 is shown, it can be seen that the air duet outlet 650 around the delivery nozzle 330 is positioned so as to heat one or boih of the edges 1.6 and 18. This heating assists with adhesion, to the molten bead 19.

10076} Locating the air heating assembly 500 parallel to the extruder as shown in Figure 1.1 and ducting the air around and over the nozzle 330 has a number of advantages. Firstly, it assists in heating the nozzle 330 during start up of the extruding assembly 300, The hot air provided by the air heating assembly 500 softens any solidified extrudate that may be blocking the nozzle 330. In addition to this pre-heat start, up function, the air heater 500 and the air ducting 600 direct air front an atinuius around the nozzle 330, so as to heat the incoming edges of the strip and extrudate bead 1 exiting the extruder.

[00771 The air heating assembly 500 will now be described in more detail with reference to Figures 10 and 11. The heat transfer element 520 is, in this embodiment of the invention* made from aluminium. Other conductive materials may be used. The aluminium heat transfer element 520 is shaped to fonn one or more helical air pathways around the air heater core 510. These pathways form air heating ducts.

[0078! The air heater core.510 consists of a low voltage, high energy density (watt density) resistance heating element that is circumferentially surrounded by the aforementioned helical air pathways within the highly thermally conductive aluminium material of the heat transfer element 520. The helical air pathways provide a. ver long pathway for the air to travel while traversing from the entrance 521 to the exit 650, This facilitates the maximum amount of thermal^' energy transferred into the passing air in a highly efficient manner,

[0Θ7 1 The ^'heat transfer element 520, in. addition to facilitating heat transfer, performs an important structural function. It functions as a central tie-rod between the end cap 560 and associated air ducting 600 and the distal body 502, A tie-rod bojt 565 connects the end ca 560 and the associated air ducting 600 to the heat transfer element 520 and hence to the distal, body 502. This. design is highly beneficial in that it obviates the need for the insulating sleeve 530 and the outer cover 5 0 to function structurally.

[0080] The insulating sleeve 530 is made from mica sheets that have an extremely low coefficient of thermal transfer and maintain- a rmnmaalist direct conductive thermal pathway to external components, such as the outer cover 550. This is important because the air heating assembly 500 is required to operate in an underground conduit where methane or other potentially flammable gasses may be present. Minimising surface temperatures is important in any hazardous (explosive gas) environment. [0081] A temperature sensor access port 690 is provided within the air ducting 600 so that the air temperature may he monitored and/or controlled.

[0082] An alternative air heating assembly 500 to that shown in Figures 10A, 1 OB and H is shown in Figures i 4 A, 14B, 15, 16A and 1633. This air heating assembly 500 has four heaters 510, 51 1 , 512. 513 disposed around an aluminium heat transfer element 520 (instead of the single heater 510 shown i Figure 11). Two of these heaters 510 and 512, in the form of cartridge heaters, are shown in the cross-sectional views of Figures 16A and 16B. Cavities or voids 510' are provided for these heater cartridges as is shown in Figure 148.

{0083] As with the air heating assembly 500 shown in Figures I OA, 10B and 1 1 , the aluminium heat transfer element 520 of Figures I4A, 14B, 15, 1.6 A and 16B is shaped to form one or more helical air pathways around the air heater core 10. These pathways form air heating ducts. A portion of one these air heating duets 522 can he seen in the cross-sect sonal view of Figure 16B.

}0084| Figures 14A and 14B also show the air inlet 521 to which the air hose 92 is connected and electrical cables 512 that feed an electrical resistance heaters that heats air entering through air inlet 521 and exiting from air duct outlet 650. An air fitting 52 la for connecting' an ah tube to the air inlet 521 is also shown.

[0085] The winding and welding machine 100 as described above is able to produce a welded pipe underground* as is illustrated diagranimatiea!ly in Figures 4 and 5. With the winding and welding machine 100, welded joints, as illustrated in Figure 7, can be produced rapidly with the production of a consistent weld bead 1 . The winding and welding machine 100 provides improved set up times and is more easily shut down and re-started than earlier known machines. The extrusion welding assembly 200 greatly reduces the need for purging and therefore reduces wastage.

10086) As is show in Figure 1 1 , the air heating assembly 500 and the extruding assembly 300 are tightly integrated into an extrusion welding assembly 200, The extrusion welding assembly 200 is compact and mounts to the drive tray 160_» as is shown in Figure ?.

(0087) While the extrusion welding assembly 200 may be attached to the drive tray 160 in a number of ways, with the embodiment illustrated in Figure 7, the attachment is by way of a drive tray extrusion welding interface assembly 700. This interface assembly 700 is illustrated in Figures 12 and 13 in more detail,

[0088] Figure 12 shows a base 71 that can be bolted or screwed to the drive tray 160 in the position illustrated in Figure 7. The interface assembly 700 includes an extrusion welding assembly frame mounting plate 740 that is configured to receive a extrusion welding assembly frame 750, as illustrated in Figure 13. The extrusion welding assembly frame 750 includes, clamps 760 and 770 that bold the extruding assembly 300 and the air heating assembly 500 its their relative positions shown in Figure 7. The extrusion welding assembly frame 750 and the attached extrusion welding assembly 200 are easily removable from the base 710 of the interface assembly 700 and hence the drive tray 160, by simple removal of hinge pin 749, as illustrated in Figure 13, f 00891 Referring agai to Figure 12, it can be seen that a carriage 730 carries the mounting plate 740, The carriage 730 is slidably connected to the base 710 between rails 712 and 714 and is driven by a lead screw 720. The lead screw 720 is actuated by a handle in the form of an adjusting spanner 727. This enables an operator to move the delivery nozzle 330 closer or further away from the pinch rollers 70 and 71 of the drive tray 160, as is illustrated in Figure 7. Fui her adjustability is provided by a hinge angle adjuster 748, as illustrated in Figure 13, and a slot 742 and associated lock 743, as shown in Figure 12. These three degrees of adjustment provide flexibility and allow the operator to best position the nozzle 330 so as to deliver a •consistent weld,, as is- diagrammaticaiiy illustrated in Figure 5.

[009&] Throughout the specification and the claims that follow, unless the context require otherwise, the words "comprise" and "include" and variations such as "comprising" and "including" will be understood to imply the inclusio n of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0091] The reference to any prior art in this specification is not, and should not be taken as, an

acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

[0092} it will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the in vention as set forth and defined by the following claims.

Claims

CLAIMS:

L A winding and welding machine for lining an underground conduit with a helically wound pipe, the machine including;

an annular frame;

a strip guide disposed around and, supported by the annular frame, the guide arranged to guide a strip around a strip path when, the machine is in use;

a drive assembly mounted to the frame for driving the strip into the strip path in a winding direction so as to present a incoming first edge to an adjacent second edge of a wound convolution of the strip; and a extruding assembly mounted to the drive assembly or the frame, the extruding assembly including an extruder, the extruder including:

a screw having a feed throat; and

a welding rod peUetising assembly including a pelletiser for delivering pe!letised plastic to the feed throat,

wherein, in use, the extruding assembly delivers a molten bead for weldin the first and adjacent second edges of the strip.

2. The machine as claimed in claim 1 wherein the extruder includes:

a barrel, the barrel havin a proximal end and a distal end;

a delivery nozzle mounted to the proximal end of the barrel, the delivery nozzle shaped and positioned to deliver a molten bead of plastic onto the incoming first edge of the strip; and

a barrel heater assembly disposed around the barrel.

3. The machine as claimed in claim 2 wherein the barrel heater assembly is slidably removable from the proximal end of the barrel.

4. The machine as. claimed in either one of claims 2 or 3 wherein the barrel heater assembly includes;

a thermally conductive barrel heater body, the barrel heate body defining a bore for receiving the extruder barrel; and

a plurality of heaters disposed around the bore.

5. The machine as claimed in claim 4 wherei the heaters include electrical resistive heating elements,

6. The machine as claimed in claim 4 wherein the barrel heater body includes a plurality of heater cavities disposed around the bore, each heater cavity containing at least one of the plurality of heaters,

7. The machine as claimed in claim 6 wherein each heater comprises a removable cartridge heater.

8. The machine as claimed in claim 4 wherein the heaters are -encapsulated so as to prevent fluid ingress to the heating elements.

9. The machine as claimed in claim 4 including an insulating sleeve disposed around the heater body, the sleeve including layers of mica.

10. The machine as claimed in claim 2 wherein the delivery nozzle has an internal bore extending from a distal end threadably connected to the proximal end of the barrel to a proximal end and wherein the internal bore tapers in a direction from the distal end towards the proximal end,

1 1. The machine as claimed in claim 2 including an air heating assembly, the air heating assembly including:

an electrical heating element;

a heat transfer element; and

12. The machine of claim 11 wherein the heat transfer element comprises a thermally conductive air heater body, the air heater body shaped to form one or more helical air pathways around the electrical heating element.

13. The machine of claim 12 whereat the air heating assembly includes a plurality of electrical heating elements, aad wherein the ai heater body is shaped to form one or more helical air pathways around each of the electrical heating elements.

14. A winding and welding machine, for lining an underground conduit with a helically wound pipe, the machine including:

an annular frame;

a strip guide disposed around and supported by the annular frame, the guide arranged to guide a strip around a strip path when the machine is is use;

a drive assembly mounted to the frame for driving the strip downwards into the strip path in a winding direction so as to present an i ncoming first edge to an adjacent second edge of a wound convolution of the strip;

a screw having a feed throat;

a welding rod pelleiising assembly including a pelletiser for delivering pelletised plastic to the feed throat;

a barrel, the barrel having a proximal end and a distal end; and a delivery nozzle mounted to the proximal end of the barrel, the delivery nozzle shaped and positioned to deliver a molten bead of plastic onto the incoming first edge of the strip;

an air heating assembly, the air heating assembly including a hot air delivery conduit having an annular exit formed in part by the delivery nozzle of the extruder.

15. The machine as claimed in claim 14 wherein the air heating assembly includes:

an electrical heating element; and

a heat transfer element.

16. The machine of claim 15 wherein the heat transfer element comprises a thermally conductive air heater body, the air heater body shaped to form one or more helical air pathways around the electrical heating element.

17. The machine of claim 1 wherein the air heater assembly includes plurality of electrical heating elements, and wherein the air heater body is shaped to form one or more helical air pathways around each of the electrical heating elements.

18. A winding and welding machine for lining an underground conduit with a helically wound pipe, the machine including:

an annular frame:

a strip guide, disposed around and supported by the annular frame, the guide arranged to guide a strip around a strip path when the machine is in use;

a drive assembly mounted to the frame for driving the strip downwards into the strip path in a winding direction so as to present an incoming first edge to an adjacent second edge of a wound convolution of the strip;

an extruding assembly mounted to the drive assembly or the frame; and

a mount,

wherein the mount is- positioned between the extruding assembly and the drive- assembly.

19. The machine as claimed in claim 18 wherein the mount includes an Interface- assembly having: a base connected to the drive assembly; and